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- Marine Ecology, Seabirds, Environmental Impact Assessment, Foraging ecology, Disturbance Ecology, Spatial Statistics, and 8 moreAvian Ecology, Bird Migration, Bird Migration Monitoring, Ecology of Bird Migration, Evolution of Bird Migration, Partial Migration, Ecomorphology, and Feeding Habits of Waterbirdsedit
Mediterranean Gulls Larus melanocephalus were observed along the Atlantic coast of central Portugal in December 2001. The observations suggest that at least part of the Mediterranean Gull population wintering in central Portugal feeds... more
Mediterranean Gulls Larus melanocephalus were observed along the Atlantic coast of central Portugal in December 2001. The observations suggest that at least part of the Mediterranean Gull population wintering in central Portugal feeds extensively at sea and possibly during the night. In the morning, Mediterranean Gulls flew in straight lines towards the coast, where they settled on water to roost in flocks of several tens of birds. Because there were no gulls near the coast at sunrise, it is assumed that these arrivals were Mediterranean Gulls that had spent the night out at sea. With an estimated ‘ground speed ’ corrected for wind speed, it was estimated that the birds could have covered several tens of kilometres offshore between sunrise and the peak of arrivals at the coast. One late afternoon, there were no roosting birds at the coast, but foraging birds were observed which were apparently successful. The question is raised whether the foraging activity is solely restricted to t...
In order to assess the potential impacts of multiple wind farms within the Dutch North Sea on bird populations, a two-step modelling approach was applied: Step one involved constructing matrix-based population models for bird species... more
In order to assess the potential impacts of multiple wind farms within the Dutch North Sea on bird populations, a two-step modelling approach was applied: Step one involved constructing matrix-based population models for bird species occurring within the Dutch North Sea. Step two involved assessing the effects of increased mortality on these populations. The bird populations assessed included both seabirds and coastal species breeding around the North Sea region, as well as key passage migrants from a wider area. Two wind farm scenarios were modeled in order to provide estimates of the potential impact of mortality due to collisions (which was considered to have a far greater influence on mortality than disturbance or barrier effects in the specific Dutch situation). Field data collected with radar and visual observations at the OWEZ wind farm helped to inform these models. The additional mortality was then applied to the population models. For those species that are currently stabl...
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ABSTRACT
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ABSTRACT
"The Sandwich Tern Sterna sandvicensis is a Dutch Red List species with a population of 19,000 pairs in the Dutch coastal zone. It winters off the coasts of Africa and a small populations migrates into the Mediterranean... more
"The Sandwich Tern Sterna sandvicensis is a Dutch Red List species with a population of 19,000 pairs in the Dutch coastal zone. It winters off the coasts of Africa and a small populations migrates into the Mediterranean or stays even more north. In the Netherlands, breeding takes places in a small number of colonies in the Delta area and the Waddensea. In this study, Sandwich Terns from the Delta colony on the Scheelhoek (Natura 2000 SPA ‘Haringvliet’) were investigated which forage during the breeding season in Natura 2000 SPA ‘Voordelta’. In total 30 adult Sandwich Terns were equipped with radio transmitters, a colourring and a plumage colour (picrinic acid or silver nitrate solution). Thanks to these markings birds could be followed in the colonies, from airplanes and from the coast. Several birds used the sand banks off the coast of their breeding colonies to rest after the breeding season. After a short while they dispersed in western and northern direction with sightings in the northern part of the Netherlands (outside and within other colonies). These were always failed breeders, possibly scouting other colonies for future breeding places. Some of these birds even left the Dutch coasts and appeared in Scotland and Denmark. Adults with young probably dispersed into the North Sea after a short stay around the sand banks off the coast near the colonies. They probably head to more nutrient rich areas in the North Sea and adjacent areas where the young birds can practice their fishing techniques before they move south. The adults can build-up here good fat reserves before the start of migration. In September, most of the marked Sandwich Terns were south of their breeding places and during their southward migration birds were seen along the coast of France and on Lanzarote (Canary Islands). Our results showed that using markers on birds could yield good data with a resighting percentage of 20% within only one year. Furthermore, the use of plumage colouring proved to be a good method for obtaining information of individual birds as these colourings attract the attention of observers and are ‘readable’ over large distances."
Abstract: In the period 2003-2011 offshore platforms in the North Sea have been successfully used for ornithologi- cal monitoring programs following standardised observation protocols. As most seabird observers have a strong interest in... more
Abstract: In the period 2003-2011 offshore platforms in the North Sea have been successfully used for ornithologi- cal monitoring programs following standardised observation protocols. As most seabird observers have a strong interest in other large marine animals, marine mammal observations were included in these systematic observa- tion protocols for recording seabirds. Some of these programs ran for several years and the collated sightings have the potential to contribute to the knowledge on at-sea distribution of marine mammals around these platforms. However, detection of marine mammals from offshore platform has several limitations. This study showed that detection significantly increased with increasing altitude of the viewing platform and decreasing sea state. Also, in instances where observers aim to record both seabirds as well as marine mammals the latter have the potential to be missed during busy periods. Nevertheless, a total of 167 platform-based sightings of three spe...
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Research Interests: Humanities and Art
Very little is known about the postnuptial ecology of the Purple Heron. In 2007 and 2008 in total 16 Purple Herons (12 adults) received satellite transmitters. During the breeding season these herons used feeding areas at a distance of... more
Very little is known about the postnuptial ecology of the Purple Heron. In 2007 and 2008 in total 16 Purple Herons (12 adults) received satellite transmitters. During the breeding season these herons used feeding areas at a distance of 1.5-15 km from the breeding colonies. However, after breeding the adults left the colony sites for a permanent stay in these feeding areas, roosting close by at night. These feeding areas are mostly agricultural grasslands and peat marshes. This finding initiated a field search for Purple Heron night roosts in the Groene Hart region of the Netherlands. In total 483 Purple Herons were counted on roosts. In two sample areas totalling 110 km2, all roosts were located and herons counted. The average number of birds at a roost was 9.2. Based on the average heron densities in these sample areas (1.8 and 2.8 herons/km2), the total number of Purple Herons in the Groene Hart could be estimated at 1400- 2000, closely matching the estimated breeding population i...
This book begins with an introduction to generalised additive models (GAM) using stable isotope ratios from squid. In Chapter 2 we explain additive mixed effects using polar bear movement data. In Chapter 3 we apply additive mixed effects... more
This book begins with an introduction to generalised additive models (GAM) using stable isotope ratios from squid. In Chapter 2 we explain additive mixed effects using polar bear movement data. In Chapter 3 we apply additive mixed effects models on coral reef data. Ruddy turnstone data are used in Chapter 4 to explain Poisson generalised additive mixed effects models (GAMMs) using the gamm4 package. A simulation study is applied to investigate the effect unbalanced random effects. In Chapter 5 parasite data sampled on anchovy fishes are used to explain overdispersed Poisson GAMM, negative binomial GAMM, and NB-P GAMM models. We briefly discuss generalised Poisson models for underdispersed data. In Chapters 6 and 7 two-dimensional smoothers are applied on zero-inflated guillemots and harbour porpoise datasets. A short revision of zero-inflated models is included. Gamma GAMMs are applied on two-way nested tree data in Chapter 8. In Chapter 9 binary nested data are analysed using binom...
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... Atlantic Seabirds 3: 149–164. Cagnon, C., B. Lauga, G. Hémery & C. Mouchès 2004. Phylogeographic differentiation of Storm Petrels (Hydrobates pelagicus) based on cytochrome b mitochondrial DNA variation. Marine Biology 145:... more
... Atlantic Seabirds 3: 149–164. Cagnon, C., B. Lauga, G. Hémery & C. Mouchès 2004. Phylogeographic differentiation of Storm Petrels (Hydrobates pelagicus) based on cytochrome b mitochondrial DNA variation. Marine Biology 145: 1257-1264. D'Elbee, J., & G. Hemery 1997. ...
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... of increased energy expenditure and the concomitant risk to die earlier of fuel exhaustion (eg the 'frost flights' of waders described by Van Eerden 1977, Camphuysen ... After a calibration time of 1.5-2 h in a dark... more
... of increased energy expenditure and the concomitant risk to die earlier of fuel exhaustion (eg the 'frost flights' of waders described by Van Eerden 1977, Camphuysen ... After a calibration time of 1.5-2 h in a dark box, a few 25-50 III blood sam-ples were taken from the brachial vein ...
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Page 1. 2003 Offshore foraging of Mediterranean Gulls in winter 1 OFFSHORE FORAGING OF MEDITERRANEAN GULLS LARUS MELA OCEPHALUS IN PORTUGAL DURING THE WINTER MARTIN POOT Poot M. 2003. Offshore ...
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Poot, M.J.M, Roelen, B.A.J. & Piersma, T. 2014. Red Knots scavenging on large, dying cockles: opportunistic feeding by a sensory specialized mollusc-crushing shorebird. Wader Study Group Bull. 121(1): 33–42. Despite their specializations,... more
Poot, M.J.M, Roelen, B.A.J. & Piersma, T. 2014. Red Knots scavenging on large, dying cockles: opportunistic feeding by a sensory specialized mollusc-crushing shorebird. Wader Study Group Bull. 121(1): 33–42. Despite their specializations, shorebirds can be opportunistic foragers during the non-breeding season. We describe how a highly specialized probe-feeding shorebird, the Red Knot Calidris canutus, suddenly ignored its shallow buried hard-shelled mollusc prey and opportunistically shifted to an unusual prey type: dying and dead cockles of size classes larger than 25 mm that were lying with gaping shells on the mud surface. Such prey items are normally not available because they are too large to be swallowed and too hard to be crushed in the gizzard. In the last week of August 1990, thousands of Red Knots arrived near Schiermonnikoog in the eastern part of the Dutch Wadden Sea. These birds belonged to the subspecies Calidris canutus islandica that winters at intertidal wetlands in...
Research Interests: Biology, Ecology, Wadden Sea, Population, Predation, and 8 moreFishery, Scavenging, Gizzard, Intertidal Zone, Red Knot, Shorebird, Cockle, and Macoma balthica
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Despite their specializations, shorebirds can be opportunistic foragers during the non-breeding season. We describe how a highly specialized probe-feeding shorebird, the Red Knot Calidris canutus, suddenly ignored its shallow buried... more
Despite their specializations, shorebirds can be opportunistic foragers during the non-breeding season. We
describe how a highly specialized probe-feeding shorebird, the Red Knot Calidris canutus, suddenly ignored
its shallow buried hard-shelled mollusc prey and opportunistically shifted to an unusual prey type: dying and
dead cockles of size classes larger than 25 mm that were lying with gaping shells on the mud surface. Such
prey items are normally not available because they are too large to be swallowed and too hard to be crushed
in the gizzard. In the last week of August 1990, thousands of Red Knots arrived near Schiermonnikoog in the
eastern part of the Dutch Wadden Sea. These birds belonged to the subspecies Calidris canutus islandica that
winters at intertidal wetlands in NW Europe. During the autumn study period, the diet of the approximately
20,000 birds in our study area consisted of small shallowly buried shellfish, comprising Edible Cockle Cerastoderma
edule (44.8%), Baltic Tellin Macoma balthica (36.9%) and Mudsnail Hydrobria ulvae (18.3%). In
the second week of October, the diet of the complete population present shifted to dying and dead cockles
lying on the surface of the tidal mudflats in a restricted area, ranging in lengths from 25 mm to 35 mm. The
death of the cockles was probably due to oxygen shortage caused by the decomposition of a bloom of
Noctiluca scintillans. Sampling of benthic fauna showed that the Red Knots had to deal with a relatively low
availability of small profitable shellfish, which diminished in the course of the autumn as Macoma buried
deeper. After one week of foraging on the opportunistic food source, with also many thousands of birds of
other species such as gulls Larus spp. and Eurasian Oystercatchers Haematopus ostralegus sharing the unexpected
food bonanza, almost all Red Knots left the area because the source became depleted. Foraging by
knots on the dying cockles may be explained by a combination of: (1) the seasonal decline in abundance of
harvestable ‘normal’ prey; and (2) the superior profitably of dying cockles over the alternative hard-shelled
food items. We discuss the repercussions of the diet shift from hard-shelled mollusc to soft-bodied food with
respect to gizzard atrophy.
describe how a highly specialized probe-feeding shorebird, the Red Knot Calidris canutus, suddenly ignored
its shallow buried hard-shelled mollusc prey and opportunistically shifted to an unusual prey type: dying and
dead cockles of size classes larger than 25 mm that were lying with gaping shells on the mud surface. Such
prey items are normally not available because they are too large to be swallowed and too hard to be crushed
in the gizzard. In the last week of August 1990, thousands of Red Knots arrived near Schiermonnikoog in the
eastern part of the Dutch Wadden Sea. These birds belonged to the subspecies Calidris canutus islandica that
winters at intertidal wetlands in NW Europe. During the autumn study period, the diet of the approximately
20,000 birds in our study area consisted of small shallowly buried shellfish, comprising Edible Cockle Cerastoderma
edule (44.8%), Baltic Tellin Macoma balthica (36.9%) and Mudsnail Hydrobria ulvae (18.3%). In
the second week of October, the diet of the complete population present shifted to dying and dead cockles
lying on the surface of the tidal mudflats in a restricted area, ranging in lengths from 25 mm to 35 mm. The
death of the cockles was probably due to oxygen shortage caused by the decomposition of a bloom of
Noctiluca scintillans. Sampling of benthic fauna showed that the Red Knots had to deal with a relatively low
availability of small profitable shellfish, which diminished in the course of the autumn as Macoma buried
deeper. After one week of foraging on the opportunistic food source, with also many thousands of birds of
other species such as gulls Larus spp. and Eurasian Oystercatchers Haematopus ostralegus sharing the unexpected
food bonanza, almost all Red Knots left the area because the source became depleted. Foraging by
knots on the dying cockles may be explained by a combination of: (1) the seasonal decline in abundance of
harvestable ‘normal’ prey; and (2) the superior profitably of dying cockles over the alternative hard-shelled
food items. We discuss the repercussions of the diet shift from hard-shelled mollusc to soft-bodied food with
respect to gizzard atrophy.
Research Interests:
In the period 2003-2011 offshore platforms in the North Sea have been successfully used for ornithological monitoring programs following standardised observation protocols. As most seabird observers have a strong interest in other large... more
In the period 2003-2011 offshore platforms in the North Sea have been successfully used for ornithological
monitoring programs following standardised observation protocols. As most seabird observers have a strong
interest in other large marine animals, marine mammal observations were included in these systematic observation
protocols for recording seabirds. Some of these programs ran for several years and the collated sightings have
the potential to contribute to the knowledge on at-sea distribution of marine mammals around these platforms.
However, detection of marine mammals from offshore platform has several limitations. This study showed that
detection significantly increased with increasing altitude of the viewing platform and decreasing sea state. Also,
in instances where observers aim to record both seabirds as well as marine mammals the latter have the potential
to be missed during busy periods. Nevertheless, a total of 167 platform-based sightings of three species of marine
mammal were collected during standardised counts on 132 observation days between 2003 and 2011. The ‘seabird’
observation protocols used have limitations for monitoring marine mammals but were useful to elucidate trends.
In this study it was demonstrated that densities recorded from platforms were up to three orders of magnitude
lower than during dedicated aerial marine mammal surveys but were comparable to ship-based surveys and aerial
surveys that recorded both birds and marine mammals. Provided that limitations are taken into consideration,
fixed platforms can provide suitable observation bases for recording the presence, relative abundance and seasonal
changes of marine mammals in offshore environments. The potential application of survey data collected
from platforms is discussed and recommendations for future work with the observation protocols used are given.
monitoring programs following standardised observation protocols. As most seabird observers have a strong
interest in other large marine animals, marine mammal observations were included in these systematic observation
protocols for recording seabirds. Some of these programs ran for several years and the collated sightings have
the potential to contribute to the knowledge on at-sea distribution of marine mammals around these platforms.
However, detection of marine mammals from offshore platform has several limitations. This study showed that
detection significantly increased with increasing altitude of the viewing platform and decreasing sea state. Also,
in instances where observers aim to record both seabirds as well as marine mammals the latter have the potential
to be missed during busy periods. Nevertheless, a total of 167 platform-based sightings of three species of marine
mammal were collected during standardised counts on 132 observation days between 2003 and 2011. The ‘seabird’
observation protocols used have limitations for monitoring marine mammals but were useful to elucidate trends.
In this study it was demonstrated that densities recorded from platforms were up to three orders of magnitude
lower than during dedicated aerial marine mammal surveys but were comparable to ship-based surveys and aerial
surveys that recorded both birds and marine mammals. Provided that limitations are taken into consideration,
fixed platforms can provide suitable observation bases for recording the presence, relative abundance and seasonal
changes of marine mammals in offshore environments. The potential application of survey data collected
from platforms is discussed and recommendations for future work with the observation protocols used are given.
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Very little is known about the postnuptial ecology of the Purple Heron. In 2007 and 2008 in total 16 Purple Herons (12 adults) received satellite transmitters. During the breeding season these herons used feeding areas at a distance of... more
Very little is known about the postnuptial ecology of the Purple Heron. In 2007 and 2008 in total 16 Purple Herons (12 adults) received satellite transmitters. During the breeding season these herons used feeding areas at a distance of 1.5-15 km from the breeding colonies. However, after breeding the adults left the colony sites for a permanent stay in these feeding areas, roosting
close by at night. These feeding areas are mostly agricultural
grasslands and peat marshes. This finding initiated a field search for Purple Heron night roosts in the Groene Hart region of the Netherlands. In total 483 Purple Herons were counted on roosts. In two sample areas totalling 110 km2, all roosts were located and herons counted. The average number of birds at a roost was 9.2. Based on the average heron densities in these sample areas
(1.8 and 2.8 herons/km2), the total number of Purple Herons in the Groene Hart could be estimated at 1400-2000, closely matching the estimated breeding population including fledglings. This confirms that almost all Purple Herons stay for some time in feeding areas prior to southward migration. From a conservation perspective it is important to note that only 10.5 % of the feeding
habitat is situated within Natura 2000 sites. Potential future
impacts on the feeding habitat are discussed. Purple Herons start their migration to Africa around the end of August. In contrast to previous assumptions, the herons do not depart from their breeding colonies, but directly from the feeding areas. This explains the high numbers observed during evening migration counts at Ridderkerk (478-694 departing herons in 2002-05). In the feeding areas north and northeast of this site, 470-930
Purple Herons are estimated to stage. The 900-1100 herons from other feeding areas will probably migrate mainly to the east of this counting site. This means that Purple Herons depart from the Netherlands in a broad front with some concentrations due to landscape characteristics and aggregation into migratory flocks.
close by at night. These feeding areas are mostly agricultural
grasslands and peat marshes. This finding initiated a field search for Purple Heron night roosts in the Groene Hart region of the Netherlands. In total 483 Purple Herons were counted on roosts. In two sample areas totalling 110 km2, all roosts were located and herons counted. The average number of birds at a roost was 9.2. Based on the average heron densities in these sample areas
(1.8 and 2.8 herons/km2), the total number of Purple Herons in the Groene Hart could be estimated at 1400-2000, closely matching the estimated breeding population including fledglings. This confirms that almost all Purple Herons stay for some time in feeding areas prior to southward migration. From a conservation perspective it is important to note that only 10.5 % of the feeding
habitat is situated within Natura 2000 sites. Potential future
impacts on the feeding habitat are discussed. Purple Herons start their migration to Africa around the end of August. In contrast to previous assumptions, the herons do not depart from their breeding colonies, but directly from the feeding areas. This explains the high numbers observed during evening migration counts at Ridderkerk (478-694 departing herons in 2002-05). In the feeding areas north and northeast of this site, 470-930
Purple Herons are estimated to stage. The 900-1100 herons from other feeding areas will probably migrate mainly to the east of this counting site. This means that Purple Herons depart from the Netherlands in a broad front with some concentrations due to landscape characteristics and aggregation into migratory flocks.
The most comprehensive survey to date of the wader population of the coast of Sierra Leone was carried out during Jan–Feb 2005. A total of 66,292 waders of 25 species were counted and the total wader population was estimated at... more
The most comprehensive survey to date of the wader population of the coast of Sierra Leone was carried out during Jan–Feb 2005. A total of 66,292 waders of 25 species were counted and the total wader population was estimated at 75,000–79,000. With a count of over 42,000, one site, Yawri Bay, accounted for over half the total. Curlew Sandpiper (24,855) was by far the most numerous species. The coast of Sierra Leone is shown to be particularly important for Common Ringed Plover and Redshank as it supports >4% of their respective flyway populations. We recommend that Yawri Bay and Sherbro Island be designated as wetlands of international importance under the Ramsar Convention.
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In order to cope with exceptional peak discharges in the river Rhine and avoid further dike-construction works, scenarios to enlarge the winterbed of the river are currently being investigated. These do not only address the purpose of... more
In order to cope with exceptional peak discharges in the river Rhine and avoid further dike-construction works, scenarios to enlarge the winterbed of the river are currently being investigated. These do not only address the purpose of safety, but also allow ecological rehabilitation of some of the original river dynamics. Ecological rehabilitation is included in the targets concerning management policies along the rivers Meuse and Rhine and their tributaries. One of the measures to achieve a
larger winterbed includes artificial lowering of the forelands. In two already artificially lowered floodplain areas along the river Rhine (Waal), an extensive study was carried out to monitor the ecological effects of the measures in a series of drier and wetter years. This paper discusses some of the effects to be expected
when floodplains in the winterbed are subject to more dynamic water tables. It is clearly demonstrated that waterbirds and waterside birds (e.g. waders, gulls) may profit from the generally wetter conditions in the lowest parts of the floodplain and/or in years with higher discharges (Tab. 1, Figs. 4-8). On the other
hand, both feeding and nesting conditions (particularly for ground-nesting terrestrial birds) may become far less favourable and some characteristic and scarce birds of less dynamic riverine landscapes (e.g. Corncrake, Corn Bunting) may even go extinct as a result of the measures. If widening the winterbed by
lowering the floodplain level will be the only way to assure safety in the Dutch river area, compensation for losses of important natural values should be offered outside the floodplain,
behind the dikes. Here, ground-level is often lower than in the floodplain in the actual winterbed, and thus opportunities exist to establish compensation areas.
Summary of statistical modeling (factors water level, winter,and year; the latter for Afferdensche en Deestsche Waarden only) to
investigate relationships between water tables and bird abundance in the floodplain of Afferdensche & Deestsche Waard and Stiftsche Waard. All possible models were examined
using loglinear regression. Only significant Pvalues for well-fitting models are included, +/- indicating the direction of the relationship. Species with significant effects of river water levels
are marked with ‘*’. Water months (indicating the period over which daily water levels were summed) 123 = Jan-Mar, 34 =Mar-Apr,45= Apr-May, 56 = May-Jun.
larger winterbed includes artificial lowering of the forelands. In two already artificially lowered floodplain areas along the river Rhine (Waal), an extensive study was carried out to monitor the ecological effects of the measures in a series of drier and wetter years. This paper discusses some of the effects to be expected
when floodplains in the winterbed are subject to more dynamic water tables. It is clearly demonstrated that waterbirds and waterside birds (e.g. waders, gulls) may profit from the generally wetter conditions in the lowest parts of the floodplain and/or in years with higher discharges (Tab. 1, Figs. 4-8). On the other
hand, both feeding and nesting conditions (particularly for ground-nesting terrestrial birds) may become far less favourable and some characteristic and scarce birds of less dynamic riverine landscapes (e.g. Corncrake, Corn Bunting) may even go extinct as a result of the measures. If widening the winterbed by
lowering the floodplain level will be the only way to assure safety in the Dutch river area, compensation for losses of important natural values should be offered outside the floodplain,
behind the dikes. Here, ground-level is often lower than in the floodplain in the actual winterbed, and thus opportunities exist to establish compensation areas.
Summary of statistical modeling (factors water level, winter,and year; the latter for Afferdensche en Deestsche Waarden only) to
investigate relationships between water tables and bird abundance in the floodplain of Afferdensche & Deestsche Waard and Stiftsche Waard. All possible models were examined
using loglinear regression. Only significant Pvalues for well-fitting models are included, +/- indicating the direction of the relationship. Species with significant effects of river water levels
are marked with ‘*’. Water months (indicating the period over which daily water levels were summed) 123 = Jan-Mar, 34 =Mar-Apr,45= Apr-May, 56 = May-Jun.
Research Interests:
"In the Netherlands and other countries around the North Sea many initiatives arise to build off shore wind farms in the North Sea. Wind turbines are known to cause collision victims among local and migrant birds. As part of an... more
"In the Netherlands and other countries around the North Sea many initiatives arise to build off shore wind farms in the North Sea. Wind turbines are known to cause collision victims among local and migrant birds. As part of an environmental assessment one of the issues is to make an estimate of the number of expected bird victims and the consequences for the population of defined species.
Especially for multi wind farm plans the number of victims might reach critical limits on population level for a species. We developed multiple stage population models based on matrix algebra (cf. Caswell 2001) to estimate the effect of additional mortality (depending on stage and period of the year) on the population. In the modelling special attention is given to a floater stage (non-breeding adults cf. Newton 1998) in these populations. For this purpose, literature data on life history and population variables, such as mortality, reproduction, and floater percentages were gathered, and models were built and calibrated with past population trends.
The results of this study gives an idea on the size of the effects at (sub)population level of one or more wind farms. The model can also be used to calculate the additional mortality that causes a population to decline. This approach can be applied for every species, and for every part of a population, as long as basic data on life history traits are available.
"
Especially for multi wind farm plans the number of victims might reach critical limits on population level for a species. We developed multiple stage population models based on matrix algebra (cf. Caswell 2001) to estimate the effect of additional mortality (depending on stage and period of the year) on the population. In the modelling special attention is given to a floater stage (non-breeding adults cf. Newton 1998) in these populations. For this purpose, literature data on life history and population variables, such as mortality, reproduction, and floater percentages were gathered, and models were built and calibrated with past population trends.
The results of this study gives an idea on the size of the effects at (sub)population level of one or more wind farms. The model can also be used to calculate the additional mortality that causes a population to decline. This approach can be applied for every species, and for every part of a population, as long as basic data on life history traits are available.
"
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In order to assess the potential impacts of multiple wind farms within the Dutch North Sea on bird populations, a two-step modelling approach was applied: Step one involved constructing matrix-based population models for bird species... more
In order to assess the potential impacts of multiple wind farms within the Dutch North Sea
on bird populations, a two-step modelling approach was applied: Step one involved
constructing matrix-based population models for bird species occurring within the Dutch
North Sea. Step two involved assessing the effects of increased mortality on these
populations. The bird populations assessed included both seabirds and coastal species
breeding around the North Sea region, as well as key passage migrants from a wider area.
Two wind farm scenarios were modeled in order to provide estimates of the potential impact
of mortality due to collisions (which was considered to have a far greater influence on
mortality than disturbance or barrier effects in the specific Dutch situation). Field data
collected with radar and visual observations at the OWEZ wind farm helped to inform these
models. The additional mortality was then applied to the population models. For those
species that are currently stable or increasing, the influence of this additional mortality was
very limited. Also for the species currently in decline the additional mortality contributed little
to these trends.
on bird populations, a two-step modelling approach was applied: Step one involved
constructing matrix-based population models for bird species occurring within the Dutch
North Sea. Step two involved assessing the effects of increased mortality on these
populations. The bird populations assessed included both seabirds and coastal species
breeding around the North Sea region, as well as key passage migrants from a wider area.
Two wind farm scenarios were modeled in order to provide estimates of the potential impact
of mortality due to collisions (which was considered to have a far greater influence on
mortality than disturbance or barrier effects in the specific Dutch situation). Field data
collected with radar and visual observations at the OWEZ wind farm helped to inform these
models. The additional mortality was then applied to the population models. For those
species that are currently stable or increasing, the influence of this additional mortality was
very limited. Also for the species currently in decline the additional mortality contributed little
to these trends.
Research Interests:
The Balearic Shearwater (Puffinus mauretanicus) is a critically endangered species, following IUCN criteria, that shows a population decline. It’s most recent total population has been estimated around 25,000 birds, with a breeding... more
The Balearic Shearwater (Puffinus mauretanicus) is a critically endangered species, following IUCN criteria, that shows a population decline. It’s most recent total population has been estimated around 25,000 birds, with a breeding population of 3,200 pairs. It’s breeding distribution is confined to the Balearic Islands,
in the western Mediterranean. Outside the breeding season the species occurs also in a wide area along the European Atlantic coasts. With a declining population up-to-date information is important for conservation strategies. Three out of the four marine IBAs located in Continental Portugal hold relevant numbers of the
species, and for two of them (PTM01 and PTM03) the Balearic shearwater is the key seabird species.
The study and monitoring of this species has been an ongoing process for SPEA and it’s volunteers since 2005, when the first coastal and ship-based surveys took place within the Marine IBA LIFE project. Since then, several other projects keep the species under focus (Species Guardian, FAME, MARPRO), together with the monthly coastal surveys organized by the Iberian seawatching network (RAM). In this study we focus on the monitoring from fixed sea watching points and analyse the heterogeneus patterns found in the coastal flights of this species. Question is how to interpret coastal flights, especially in relation to the distinction between local versus migratory movements. At some days a multiple passage peak occurred with both birds flying north and south. On other days birds either moved mainly to the north or to south, opposed to the prevailing wind of the day, which can be
interpreted as correction for drift. These flight patterns are typical for the species and have a large social aspect with birds roaming over a large area as a scattered but united flock to search for favourable foraging conditions. This behaviour can ultimately lead to large foraging concentrations. The largest flock most
recently observed amounted 9% of the total population. Some of these coastal concentrations were associated with fronts. Further out at sea also associations with fishery occur. The patterns of coastal flights are further discussed in relation to what is known on the occurrence of concentration areas, mainly based on
ship- and aerial-based surveys.
For a better interpretation of coastal flights it is recommended that timing and flight directions are recorded in more detail. Furthermore, as concentrations of this nearshore species can be detected form the shore, in addition specific search actions could be rewarding, especially covering parts of the coast where
large concentrations can be expected based on observed coastal flights. In this way shore based observations could serve as a basic monitoring tool for this species, besides the necessary, but more costly aerial-based and/or ship-based surveys for a complete coverage of the near- and offshore zone.
in the western Mediterranean. Outside the breeding season the species occurs also in a wide area along the European Atlantic coasts. With a declining population up-to-date information is important for conservation strategies. Three out of the four marine IBAs located in Continental Portugal hold relevant numbers of the
species, and for two of them (PTM01 and PTM03) the Balearic shearwater is the key seabird species.
The study and monitoring of this species has been an ongoing process for SPEA and it’s volunteers since 2005, when the first coastal and ship-based surveys took place within the Marine IBA LIFE project. Since then, several other projects keep the species under focus (Species Guardian, FAME, MARPRO), together with the monthly coastal surveys organized by the Iberian seawatching network (RAM). In this study we focus on the monitoring from fixed sea watching points and analyse the heterogeneus patterns found in the coastal flights of this species. Question is how to interpret coastal flights, especially in relation to the distinction between local versus migratory movements. At some days a multiple passage peak occurred with both birds flying north and south. On other days birds either moved mainly to the north or to south, opposed to the prevailing wind of the day, which can be
interpreted as correction for drift. These flight patterns are typical for the species and have a large social aspect with birds roaming over a large area as a scattered but united flock to search for favourable foraging conditions. This behaviour can ultimately lead to large foraging concentrations. The largest flock most
recently observed amounted 9% of the total population. Some of these coastal concentrations were associated with fronts. Further out at sea also associations with fishery occur. The patterns of coastal flights are further discussed in relation to what is known on the occurrence of concentration areas, mainly based on
ship- and aerial-based surveys.
For a better interpretation of coastal flights it is recommended that timing and flight directions are recorded in more detail. Furthermore, as concentrations of this nearshore species can be detected form the shore, in addition specific search actions could be rewarding, especially covering parts of the coast where
large concentrations can be expected based on observed coastal flights. In this way shore based observations could serve as a basic monitoring tool for this species, besides the necessary, but more costly aerial-based and/or ship-based surveys for a complete coverage of the near- and offshore zone.
Research Interests:
Research Interests:
In the last decade, marine surveillance radars positioned vertically have been used to gather information on numbers of birds aloft during the night. This type of radar is easy in operational use and relatively cheap, and therefore used... more
In the last decade, marine surveillance radars positioned vertically have been used to gather information on numbers of
birds aloft during the night. This type of radar is easy in operational use and relatively cheap, and therefore used in many
studies in Europe within the framework of estimating potential effects of wind turbines on birds. Herewith especially the
study of migration/local movements at low altitudes (<200 m) is most relevant. Information on migration at higher
altitudes, however, places migration at low altitudes in a broader perspective and for this reason is often studied as well,
although here the detection probability decreases due to limitations of the radar. A unit of measurement of bird flights
that is often used in order to compare different studies is Migration Traffic Rate (MTR); this is the number of birds
passing per hour per kilometre. In order to arrive at this unit in the first place one has to correct for passages not
perpendicular to the radar beam. Furthermore, apart from radar characteristics (power, wave/pulse length), weather
conditions (humidity), features of the bird, such as its size, in combination with heading/flight direction, mainly
determine whether a bird is detected or not as the reflect ability or radar cross section varies with the position of the bird
relative to the radar, with birds that are beamed from the side having the largest radar cross section. This aspect can
substantially affect the effective beam shape (both range and width) and therefore recorded fluxes. In this paper, an
update in insights is given on the factors limiting the detection probability and what the consequences are for the recorded
MTR. This is illustrated by results gathered during different studies performed at various locations in the Netherlands.
With this evaluation of the use of vertical surveillance radar for quantifying bird flux, recommendations are given on how
to interpret/correct MTRs gathered by vertical marine surveillance radars.
birds aloft during the night. This type of radar is easy in operational use and relatively cheap, and therefore used in many
studies in Europe within the framework of estimating potential effects of wind turbines on birds. Herewith especially the
study of migration/local movements at low altitudes (<200 m) is most relevant. Information on migration at higher
altitudes, however, places migration at low altitudes in a broader perspective and for this reason is often studied as well,
although here the detection probability decreases due to limitations of the radar. A unit of measurement of bird flights
that is often used in order to compare different studies is Migration Traffic Rate (MTR); this is the number of birds
passing per hour per kilometre. In order to arrive at this unit in the first place one has to correct for passages not
perpendicular to the radar beam. Furthermore, apart from radar characteristics (power, wave/pulse length), weather
conditions (humidity), features of the bird, such as its size, in combination with heading/flight direction, mainly
determine whether a bird is detected or not as the reflect ability or radar cross section varies with the position of the bird
relative to the radar, with birds that are beamed from the side having the largest radar cross section. This aspect can
substantially affect the effective beam shape (both range and width) and therefore recorded fluxes. In this paper, an
update in insights is given on the factors limiting the detection probability and what the consequences are for the recorded
MTR. This is illustrated by results gathered during different studies performed at various locations in the Netherlands.
With this evaluation of the use of vertical surveillance radar for quantifying bird flux, recommendations are given on how
to interpret/correct MTRs gathered by vertical marine surveillance radars.
Research Interests: Radar and Bird Migration
Research Interests:
"Quantitative information on the volume of flight movements of birds and flight altitudes is necessary in order to be able to estimate collision risks with wind turbines. This information is often insufficiently known, both of local bird... more
"Quantitative information on the volume of flight movements of birds and flight altitudes is necessary in order to be able to estimate collision risks with wind turbines. This information is often insufficiently known, both of local bird movements and of seasonal migration.
Marine surveillance radars positioned vertically can be used to gather this information, allowing measurements of altitude profiles of bird flights. For the assessment of the potential effect of wind turbines on bird migration, especially the study of migration at low altitudes (<200 m) is most relevant. Information on migration at higher altitudes however does place migration at low altitudes in a broader perspective and for this reason is often studied as well, although here detection loss takes place due to limitations of the radar (power).
The combination of wave/pulse length, the power of the radar, and weather conditions determine the detection of birds by radar. On the other hand detection is dependent on ‘bird aspects’. Detection loss occurs in relation to the combination of species/size of the birds, the distance or height of birds, but also heading and flight direction of birds plays a role.
Birds that are beamed head-front by the radar are less visible than birds that are beamed from the side (largest radar cross section). This aspect can substantially affect the recorded fluxes. In this paper, based on studies performed at different locations in the Netherlands, the consequences for the recorded Migration Traffic Rate are shown and the necessary corrections are suggested.
"
Marine surveillance radars positioned vertically can be used to gather this information, allowing measurements of altitude profiles of bird flights. For the assessment of the potential effect of wind turbines on bird migration, especially the study of migration at low altitudes (<200 m) is most relevant. Information on migration at higher altitudes however does place migration at low altitudes in a broader perspective and for this reason is often studied as well, although here detection loss takes place due to limitations of the radar (power).
The combination of wave/pulse length, the power of the radar, and weather conditions determine the detection of birds by radar. On the other hand detection is dependent on ‘bird aspects’. Detection loss occurs in relation to the combination of species/size of the birds, the distance or height of birds, but also heading and flight direction of birds plays a role.
Birds that are beamed head-front by the radar are less visible than birds that are beamed from the side (largest radar cross section). This aspect can substantially affect the recorded fluxes. In this paper, based on studies performed at different locations in the Netherlands, the consequences for the recorded Migration Traffic Rate are shown and the necessary corrections are suggested.
"
Research Interests: Radar and Bird Migration
Research Interests:
In commission of the Royal Netherlands Air Force and the City of Eindhoven we registered the number of birds aloft on Eindhoven Airport between August 1998 and July 1999 by visual techniques using binoculars. Observations were conducted... more
In commission of the Royal Netherlands Air Force and the City of Eindhoven
we registered the number of birds aloft on Eindhoven Airport between August
1998 and July 1999 by visual techniques using binoculars. Observations were
conducted during four days each month and lasted the full daylight period.
Two methods were used: observations in a fixed volume covering a part of the
runway and bordering fields (fixed volume count) and observations in a radarlike
way covering a much larger volume consisting of the total airport and
surrounding landscape (horizon-scan). The focus of this paper is on the
second technique.
Since the risk of bird strike is highest during take off and landing (i.e. the lower
air layers), it is important to know the density and species composition of birds
that are flying near and over runways. Questions from the perspective of bird
strike risk and bird control are whether the numbers and species composition
of birds flying over the runways show a relation with the surrounding
landscape of the airport and whether bird flight routes occur in relation to
landscape structures. Eindhoven Airport has an open landscape and is
located in a forested area in the southeast of The Netherlands.
As the panorama-scan covers a much wider area than the single runway of
Eindhoven Airport (as in the case of the fixed volume scan) this visual
technique gives the opportunity to compare and relate the numbers of birds
aloft above as well as around the airport. In this paper we show that with this
technique, besides reliable information on densities of birds aloft, at the same
time detailed spatial and flight direction information is gathered which makes it
2 Poot et al.
possible to interpret the estimates of densities of birds aloft in an ecological
context.
Key Words: Visual detection, Local movements, Risk assessment, Migration, Bird density, Bird strike, Aircraft, Collision risk
we registered the number of birds aloft on Eindhoven Airport between August
1998 and July 1999 by visual techniques using binoculars. Observations were
conducted during four days each month and lasted the full daylight period.
Two methods were used: observations in a fixed volume covering a part of the
runway and bordering fields (fixed volume count) and observations in a radarlike
way covering a much larger volume consisting of the total airport and
surrounding landscape (horizon-scan). The focus of this paper is on the
second technique.
Since the risk of bird strike is highest during take off and landing (i.e. the lower
air layers), it is important to know the density and species composition of birds
that are flying near and over runways. Questions from the perspective of bird
strike risk and bird control are whether the numbers and species composition
of birds flying over the runways show a relation with the surrounding
landscape of the airport and whether bird flight routes occur in relation to
landscape structures. Eindhoven Airport has an open landscape and is
located in a forested area in the southeast of The Netherlands.
As the panorama-scan covers a much wider area than the single runway of
Eindhoven Airport (as in the case of the fixed volume scan) this visual
technique gives the opportunity to compare and relate the numbers of birds
aloft above as well as around the airport. In this paper we show that with this
technique, besides reliable information on densities of birds aloft, at the same
time detailed spatial and flight direction information is gathered which makes it
2 Poot et al.
possible to interpret the estimates of densities of birds aloft in an ecological
context.
Key Words: Visual detection, Local movements, Risk assessment, Migration, Bird density, Bird strike, Aircraft, Collision risk
Research Interests:
In recent years, stoneworts {Chara contrarla and C. aspera) have recolonized several large Dutch freshwater lakes, as a consequence of improving water quality. In Lake Veiuwemeer, Pondweed-species (Potamogeton pectlnatus, P.... more
In recent years, stoneworts {Chara contrarla and C. aspera)
have recolonized several large Dutch freshwater
lakes, as a consequence of improving water quality. In
Lake Veiuwemeer, Pondweed-species (Potamogeton
pectlnatus, P. perfollatus and P puslllus) occur as well,
but locally they are gradually replaced by Chara. Both
stoneworts and pondweeds are important as a food
source for large numbers of herbivorous waterbirds.
In this paper species, numbers, food choice and some
of the patterns in distribution and food-preference
throughout the season are presented.
The macrophyte species were mapped in summer (fig.
1) and biomass samples were taken regularly (fig. 2).
FromJuly 1994toJanuary 1995 waterbirds were counted
fortnightly (fig. 3). Their location and feeding activity
were recorded as well. These data were related with the vegetation maps (fig. 3). Additional observations on
feeding behaviour were more intensive and detailed in
autumn 1995.
Coot {Fuka atra) were the most numerous Cara-feeding
birds. They seemed to depiete the C/iara-stands
more or less systematically (fig. 4). The peak numbers
of IVtute swans {Cygnus oIor) almost exclusively foraged
on Chara as well. Bewick's swans (C. columbianus bewkkii),
well-known for their feeding on tubers and stolons
of Pofamogeton-spedes, soon switched to feeding
on Chara (figs. 3 & 5). In both years, they reached their
maximum numbers only after Potamogeton was apparently
depleted. In 1995, a maximum of nearly 2500
was reached. The attractiveness for Bewick's swans is
probably related to the presence of bulbils on the roots
of Chara aspera. Several species of ducks also feed on
Chara. The most numerous are Pochard (Aythya ferina),
Mallard {Anas platyrhynchos), Wigeon {A. penelopé)
and Pintail (A. acuta).
Factors determining the attractiveness of Chara for waterbirds
are lts high densities, lts relative late peak biomass
as compared to other waterplants, lts composition
(a relatively low content of crude fiber) and the presence
of bulbils. Ecologicai rehabilitation of freshwater
lakes therefore offers good opportunities for herbivorous
waterbirds.
have recolonized several large Dutch freshwater
lakes, as a consequence of improving water quality. In
Lake Veiuwemeer, Pondweed-species (Potamogeton
pectlnatus, P. perfollatus and P puslllus) occur as well,
but locally they are gradually replaced by Chara. Both
stoneworts and pondweeds are important as a food
source for large numbers of herbivorous waterbirds.
In this paper species, numbers, food choice and some
of the patterns in distribution and food-preference
throughout the season are presented.
The macrophyte species were mapped in summer (fig.
1) and biomass samples were taken regularly (fig. 2).
FromJuly 1994toJanuary 1995 waterbirds were counted
fortnightly (fig. 3). Their location and feeding activity
were recorded as well. These data were related with the vegetation maps (fig. 3). Additional observations on
feeding behaviour were more intensive and detailed in
autumn 1995.
Coot {Fuka atra) were the most numerous Cara-feeding
birds. They seemed to depiete the C/iara-stands
more or less systematically (fig. 4). The peak numbers
of IVtute swans {Cygnus oIor) almost exclusively foraged
on Chara as well. Bewick's swans (C. columbianus bewkkii),
well-known for their feeding on tubers and stolons
of Pofamogeton-spedes, soon switched to feeding
on Chara (figs. 3 & 5). In both years, they reached their
maximum numbers only after Potamogeton was apparently
depleted. In 1995, a maximum of nearly 2500
was reached. The attractiveness for Bewick's swans is
probably related to the presence of bulbils on the roots
of Chara aspera. Several species of ducks also feed on
Chara. The most numerous are Pochard (Aythya ferina),
Mallard {Anas platyrhynchos), Wigeon {A. penelopé)
and Pintail (A. acuta).
Factors determining the attractiveness of Chara for waterbirds
are lts high densities, lts relative late peak biomass
as compared to other waterplants, lts composition
(a relatively low content of crude fiber) and the presence
of bulbils. Ecologicai rehabilitation of freshwater
lakes therefore offers good opportunities for herbivorous
waterbirds.