Fecundity is fundamental to the fitness, population dynamics, conservation, and management of bir... more Fecundity is fundamental to the fitness, population dynamics, conservation, and management of birds. For all the efforts made to measure fecundity or its surrogates over the past century of avian research, it is still mismeasured, misrepresented, and misunderstood. Fundamentally, these problems arise because of partial observability of underlying processes such as renesting, multiple brooding, and temporary emigration. Over the last several decades, various analytical approaches have been developed to estimate fecundity from incomplete and biased data. These, include scalar arithmetic formulae, partial differential equations, individual-based simulations, and Markov chain methodology. In this paper, we: (1) identify component processes of avian reproduction; (2) review existing methods for modeling fecundity; (3) place these diverse models under a common conceptual framework; (4) describe the parameterization, validation, and limitations of such models; and (5) point out future considerations and challenges in the application of fecundity models. We hope this synthesis of existing literature will help direct researchers toward the most appropriate methods to assess avian reproductive success for answering questions in evolutionary ecology, natural history, population dynamics, reproductive toxicology, and management.
Usfws Usgs Structured Decision Making Workshop National Conservation Training Center Shepherdstown Wv January 25 29 2010, Jan 25, 2010
Conservation of oceanic island species presents many ecological and logistical challenges. The No... more Conservation of oceanic island species presents many ecological and logistical challenges. The Northwestern Hawaiian Islands (NWHI) include 300,000 km 2 of ocean waters and 10 groups of sub-tropical islands and atolls of high conservation value. Designated as Papahanaumokuakea Marine National Monument, the islands provide habitat for four endangered species of terrestrial birds. Despite their protected status, many of these species are faced with the ongoing threat of extinction due to stochastic catastrophes such as disease, invasive mammal introductions, tsunamis, and hurricanes. To reduce the risk that a single catastrophe would lead to extinction, managers propose to restore multiple "insurance" populations on islands currently unoccupied by these species to increase their range and overall numbers.
1. Understanding the distribution and ecology of episodic or mobile species requires us to addres... more 1. Understanding the distribution and ecology of episodic or mobile species requires us to address multiple potential biases, including spatial clustering of survey locations, imperfect detectability and partial availability for detection. These challenges have been addressed individually by previous modelling approaches, but there is currently no extension of the occupancy modelling framework that accounts for all three problems while estimating occupancy (w), availability for detection (i.e. use; h) and detectability (P). 2. We describe a hierarchical Bayes multi-scale occupancy model that simultaneously estimates site occupancy, use, and detectability, while accounting for spatial dependence through a state-space approach based on repeated samples at multiple spatial or temporal scales. As an example application, we analyse the spatiotemporal distribution of the Louisiana waterthrush Seiurus motacilla with respect to catchment size and availability of potential prey based on data collected along Appalachian streams of southern West Virginia, USA. In spring 2009, single observers recorded detections of Louisiana waterthrush (henceforth, waterthrush) within 75 m of point-count stations (i.e. sites) during four 5-min surveys per site, with each survey broken into 1-min intervals. 3. Waterthrushes were widely distributed (w range: 0AE6-1AE0) and were regularly using (h range: 0AE4-0AE6) count circles along forested mountain streams. While accounting for detection biases and spatial dependence among nearby sampling sites, waterthrushes became more common as catchment area increased, and they became more available for detection as the per cent of the benthic macroinvertebrates that were of the orders Ephemeroptera, Plecoptera or Trichoptera (EPT) increased. These results lend some support to the hypothesis that waterthrushes are influenced by instream conditions as mediated by watershed size and benthic macroinvertebrate community composition. 4. Synthesis and applications. Although several available modelling techniques provide estimates of occupancy at one scale, hierarchical Bayes multi-scale occupancy modelling provides estimates of distribution at two scales simultaneously while accounting for detection biases and spatial dependencies. Hierarchical Bayes multi-scale occupancy models therefore hold significant potential for addressing complex conservation threats that operate at a landscape scale (e.g. climate change) and probably influence species distributions over multiple scales.
Avian monitoring is a regular component of long-term programs that evaluate changes in ecological... more Avian monitoring is a regular component of long-term programs that evaluate changes in ecological integrity following natural and anthropogenic disturbance. While bird species or guilds can serve as cost-effective indicators of such changes, accounting for imperfect detection of birds in avian monitoring programs remains a challenge. Indeed, few studies have accounted for detectability while estimating bird occupancy and abundance. We used an information-theoretic approach to model species-and guild-specifi c occupancy (ψ) and detection probabilities (p), based on bird surveys along streams in two national parks of southern West Virginia. A species-specifi c occupancy model was much more parsimonious than a guild-specifi c occupancy model, which was in turn much more parsimonious than one that assumed all species were distributed equally across the study areas. Detectability varied among guilds and species within guilds, visit occasions, observers, and stream noise levels. Even while accounting for low detectability (p < 30%), predicted occupancy was low for some species (ψ < 35%). Other species, though, had high detectability (p > 65%) and high occupancy (ψ ≥ 90%). Species with detection probabilities above 30% (to better ensure accurate occupancy estimates given our study design) represented all of the open-cup-nesting, forest-interior songbird guilds, and these are therefore good candidate indicators for a long-term monitoring program aimed at identifying annual changes in occupancy. The occupancy modeling approach provides a robust, extensible framework for long-term monitoring of individual bird species and entire communities, which can be linked to other measures of ecosystem integrity.
ABSTRACT Headwater forests serve many ecological functions and may be particularly responsive to ... more ABSTRACT Headwater forests serve many ecological functions and may be particularly responsive to changes in climate and land use. Riparian birds can serve as indicators of changes in their associated ecosystems. Little known, however, are combined influences of climate and land use on riparian birds and riparian ecosystems. We examined multiscale associations between these environmental conditions and reproduction of the Louisiana Waterthrush (Seiurus motacilla), a riparian-obligate songbird that breeds in the eastern United States. Specifically, we measured variables at multiple spatial and temporal scales to model crucial components of individual fecundity, using an information-theoretic approach. We monitored 190 nests in 139 territories within 13 drainages from 2002 to 2005. Daily nest survival reached a maximum when mean rainfall was intermediate (3–10 mm day–1) during the nesting period. Nestling survival, by contrast, reached its maximum with high amounts of rainfall (>14 ...
Louisiana Waterthrushes (waterthrushes; Seiurus motacilla) are infrequently studied Neotropical m... more Louisiana Waterthrushes (waterthrushes; Seiurus motacilla) are infrequently studied Neotropical migratory songbirds that breed throughout much of the southeastern U.S, which is undergoing rapid urbanization. They may serve as effective indicators of stream biotic integrity because of their dependence on riparian systems for food and nesting. Furthermore, waterthrushes are easier to survey than complex assemblages of fish and macroinvertebrates. While the
2015. Collaborative decision-analytic framework to maximize resilience of tidal marshes to climat... more 2015. Collaborative decision-analytic framework to maximize resilience of tidal marshes to climate change. Ecology and Society 20(1): 30. http://dx.
ABSTRACT Migratory species provide economically beneficial ecosystem services to people throughou... more ABSTRACT Migratory species provide economically beneficial ecosystem services to people throughout their range, yet often, information is lacking about the magnitude and spatial distribution of these benefits at regional scales. We conducted a case study for Northern Pintails (hereafter pintail) in which we quantified regional and sub-regional economic values of subsistence harvest to indigenous communities in Arctic and sub-Arctic North America. As a first step, we used the replacement cost method to quantify the cost of replacing pintail subsistence harvest with the most similar commercially available protein (chicken). For an estimated annual subsistence harvest of ˜15,000 pintail, our mean estimate of the total replacement cost was ˜$63,000 yr−1 ($2010 USD), with sub-regional values ranging from $263 yr−1 to $21,930 yr−1. Our results provide an order-of-magnitude, conservative estimate of one component of the regional ecosystem-service values of pintails, providing perspective on how spatially explicit values can inform migratory species conservation.
Six large-bodied, ≥ 120 g, woodpecker species are listed as near-threatened to critically endange... more Six large-bodied, ≥ 120 g, woodpecker species are listed as near-threatened to critically endangered by the International Union for Conservation of Nature (IUCN). The small population paradigm assumes that these populations are likely to become extinct without an increase in numbers, but the combined influences of initial population size and demographic rates, i.e., annual adult survival and fecundity, may drive
Coffee agroforestry systems and secondary forests have been shown to support similar bird communi... more Coffee agroforestry systems and secondary forests have been shown to support similar bird communities but comparing these habitat types are challenged by potential biases due to differences in detectability between habitats. Furthermore, seasonal dynamics may influence bird communities differently in different habitat types and therefore seasonal effects should be considered in comparisons. To address these issues, we incorporated seasonal effects and factors potentially affecting bird detectability into models to compare avian community composition and dynamics between coffee agroforests and secondary forest fragments. In particular, we modeled community composition and community dynamics of bird functional groups based on habitat type (coffee agroforest vs. secondary forest) and season while accounting for variation in capture probability (i.e. detectability). The models we used estimated capture probability to be similar between habitat types for each dietary guild, but omnivores had a lower capture probability than frugivores and insectivores. Although apparent species richness was higher in coffee agroforest than secondary forest, model results indicated that omnivores and insectivores were more common in secondary forest when accounting for heterogeneity in capture probability. Our results largely support the notion that shade-coffee can serve as a surrogate habitat for secondary forest with respect to avian communities. Small coffee agroforests embedded within the typical tropical countryside matrix of secondary forest patches and small-scale agriculture, therefore, may host avian communities that resemble those of surrounding secondary forest, and may serve as viable corridors linking patches of forest within these landscapes. This information is an important step toward effective landscape-scale conservation in Neotropical agricultural landscapes.
Understanding interactions between mobile species distributions and landcover characteristics rem... more Understanding interactions between mobile species distributions and landcover characteristics remains an outstanding challenge in ecology. Multiple factors could explain species distributions including endogenous evolutionary traits leading to conspecific clustering and endogenous habitat features that support life history requirements. Birds are a useful taxon for examining hypotheses about the relative importance of these factors among species in a community. We developed a hierarchical Bayes approach to model the relationships between bird species occupancy and local landcover variables accounting for spatial autocorrelation, species similarities, and partial observability. We fit alternative occupancy models to detections of 90 bird species observed during repeat visits to 316 point-counts forming a 400-m grid throughout the Patuxent Wildlife Research Refuge in Maryland, USA. Models with landcover variables performed significantly better than our autologistic and null models, supporting the hypothesis that local landcover heterogeneity is important as an exogenous driver for species distributions. Conspecific clustering alone was a comparatively poor descriptor of local community composition, but there was evidence for spatial autocorrelation in all species. Considerable uncertainty remains whether landcover combined with spatial autocorrelation is most parsimonious for describing bird species distributions at a local scale. Spatial structuring may be weaker at intermediate scales within which dispersal is less frequent, information flows are localized, and landcover types become spatially diversified and therefore exhibit little aggregation. Examining such hypotheses across species assemblages contributes to our understanding of community-level associations with conspecifics and landscape composition.
Rivers may serve as reservoirs for enteric organisms. Very little is known about the boundaries o... more Rivers may serve as reservoirs for enteric organisms. Very little is known about the boundaries of microbial communities in moving bodies of water so this study was undertaken to find the limits of distribution of some bacteria, focusing on enteric organisms. The presence of Salmonella, Campylobacter, and Enterococcus spp. and the antimicrobial resistance phenotypes carried by these organisms was evaluated for the Upper Oconee River basin, a small river in the lower Piedmont of northeastern Georgia, USA. Samples were obtained from 83 sites during a 3h period on a spring day (April 2005) in an approximately 30×20 km region. Campylobacter spp. was isolated at 12 sites. The Campylobacter isolates from three sites were resistant to tetracycline. Of the five short-variable region (SVR) subtypes of Campylobacter that were found, three were found at more than one site, two types were found twice, and one subtype was found three times. Enterococcus was isolated at 71 sites. E. casseliflavus was the most common species. Based on species identification and antimicrobial resistance patterns, 24 types of Enterococcus were found. Salmonella was isolated from 62 sites. Of the 19 Salmonella serovars that were isolated, serovar Muenchen accounted for about 20% of the isolates. The next three most common serovars isolated, Rubislaw, Hartford, and Give, accounted for about 44% of the river isolates. Antimicrobial resistance profiling offered limited differentiation of Salmonella isolates because only seven isolates were resistant to any antimicrobial. The sites at which Salmonella, Campylobacter, or Enterococcus were isolated did not correlate with each other or with the total coliform number or Escherichia coli count for the site. However, isolates of some of the same species and type occurred in clusters that were restricted to areas within 5 to 6 km.
The Louisiana Waterthrush (waterthrush; Seiurus motacilla) is a forest-dwelling, Nearctic-Neotrop... more The Louisiana Waterthrush (waterthrush; Seiurus motacilla) is a forest-dwelling, Nearctic-Neotropical migratory passerine that nests along streams. We attached radiotransmitters (0.6-0.8 g) to 12 nestling waterthrushes using snug, elastic loops. At three nests, adult waterthrushes were videotaped removing radio-tagged young from the nest. In addition, we recovered nine radio-backpacks (with two still attached to the carcasses of nestlings) near nests within a few days after attaching transmitters. Only one of 12 radio-tagged young was relocated more than 24 h after attaching the transmitter. Thus, the method of transmitter attachment we used was not effective. Using snug, nonelastic loops (e.g., nylon) for the harness may reduce the loss of transmitters, but may injure the skin as fledglings grow. Other possible alternatives include (1) gluing the transmitter to skin on the back of nestlings, (2) capturing fledglings in mist nets and attaching transmitters a week or more after fledging by which time contour feathers have grown and the likelihood of a parent removing the transmitter may be reduced, or (3) attempting to monitor fledglings without attaching transmitters. The success of the latter two alternatives would likely be enhanced by attaching transmitters to adults and then tracking them to locate their still-dependent fledglings.
1. Understanding the distribution and ecology of episodic or mobile species requires us to addres... more 1. Understanding the distribution and ecology of episodic or mobile species requires us to address multiple potential biases, including spatial clustering of survey locations, imperfect detectability and partial availability for detection. These challenges have been addressed individually by previous modelling approaches, but there is currently no extension of the occupancy modelling framework that accounts for all three problems while estimating occupancy (w), availability for detection (i.e. use; h) and detectability (P). 2. We describe a hierarchical Bayes multi-scale occupancy model that simultaneously estimates site occupancy, use, and detectability, while accounting for spatial dependence through a state-space approach based on repeated samples at multiple spatial or temporal scales. As an example application, we analyse the spatiotemporal distribution of the Louisiana waterthrush Seiurus motacilla with respect to catchment size and availability of potential prey based on data collected along Appalachian streams of southern West Virginia, USA. In spring 2009, single observers recorded detections of Louisiana waterthrush (henceforth, waterthrush) within 75 m of point-count stations (i.e. sites) during four 5-min surveys per site, with each survey broken into 1-min intervals. 3. Waterthrushes were widely distributed (w range: 0AE6-1AE0) and were regularly using (h range: 0AE4-0AE6) count circles along forested mountain streams. While accounting for detection biases and spatial dependence among nearby sampling sites, waterthrushes became more common as catchment area increased, and they became more available for detection as the per cent of the benthic macroinvertebrates that were of the orders Ephemeroptera, Plecoptera or Trichoptera (EPT) increased. These results lend some support to the hypothesis that waterthrushes are influenced by instream conditions as mediated by watershed size and benthic macroinvertebrate community composition. 4. Synthesis and applications. Although several available modelling techniques provide estimates of occupancy at one scale, hierarchical Bayes multi-scale occupancy modelling provides estimates of distribution at two scales simultaneously while accounting for detection biases and spatial dependencies. Hierarchical Bayes multi-scale occupancy models therefore hold significant potential for addressing complex conservation threats that operate at a landscape scale (e.g. climate change) and probably influence species distributions over multiple scales.
1. Benthic stream animals, in particular macroinvertebrates, are good indicators of water quality... more 1. Benthic stream animals, in particular macroinvertebrates, are good indicators of water quality, but sampling can be laborious to obtain accurate indices of biotic integrity. Thus, tools for bioassessment that include measurements other than macroinvertebrates would be valuable additions to volunteer monitoring protocols. 2. We evaluated the usefulness of a stream-dependent songbird, the Louisiana waterthrush (waterthrush, Seiurus motacilla) and the Environmental Protection Agency Visual Habitat Assessment (EPA VHA) as indicators of the macrobenthos community in headwater streams of the Georgia Piedmont, U.S.A. We sampled macrobenthos, surveyed waterthrushes and measured habitat characteristics along 39 headwater reaches across 17 catchments ranging from forested to heavily urbanised or grazed by cattle. 3. Of the indicators considered, waterthrush occupancy was best for predicting relative abundances of macrobenthic taxa, while the EPA VHA was best for predicting Ephemeroptera-Plecoptera-Trichoptera (EPT) richness. Individual components of EPA VHA scores were much less useful as indicators of EPT richness and % EPT when compared with the total score. Waterthrushes were found along streams with higher % EPT, a lower Family Biotic Index (FBI) values and greater macrobenthos biomass. 4. While macroinvertebrates remain one of the most direct indicators of stream water quality, stream bird surveys and reach-scale habitat assessments can serve as cost-effective indicators of benthic macroinvertebrate communities. Using stream-dependent birds as an early warning signal for degradation of stream biotic integrity could improve the efficacy of catchment monitoring programmes in detecting and identifying perturbations within the catchment.
We developed and evaluated the performance of a metapopulation model enabling managers to examine... more We developed and evaluated the performance of a metapopulation model enabling managers to examine, for the first time, the consequences of alternative management strategies involving habitat conditions and hunting on both harvest opportunity and carrying capacity (i.e., equilibrium population size in the absence of harvest) for migratory waterfowl at a continental scale. Our focus is on the northern pintail (Anas acuta; hereafter, pintail), which serves as a useful model species to examine the potential for integrating waterfowl harvest and habitat management in North America. We developed submodel structure capturing important processes for pintail populations during breeding, fall migration, winter, and spring migration while encompassing spatial structure representing three core breeding areas and two core nonbreeding areas. A number of continental-scale predictions from our baseline parameterization (e.g., carrying capacity of 5.5 million, equilibrium population size of 2.9 million and harvest rate of 12% at maximum sustained yield [MSY]) were within 10% of those from the pintail harvest strategy under current use by the U.S. Fish and Wildlife Service. To begin investigating the interaction of harvest and habitat management, we examined equilibrium population conditions for pintail at the continental scale across a range of harvest rates while perturbing model parameters to represent: (1) a 10% increase in breeding habitat quality in the Prairie Pothole population (PR); and (2) a 10% increase in nonbreeding habitat quantity along in the Gulf Coast (GC). Based on our model and analysis, a greater increase in carrying capacity and sustainable harvest was seen when increasing a proxy for habitat quality in the Prairie Pothole population. This finding and underlying assumptions must be critically evaluated, however, before specific management recommendations can be made. To make such recommendations, we require (1) extended, refined submodels with additional parameters linking influences of habitat management and environmental conditions to key life-history parameters; (2) a formal sensitivity analysis of the revised model; (3) an integrated population model that incorporates empirical data for estimating key vital rates; and (4) cost estimates for changing these additional parameters through habitat management efforts. We foresee great utility in using an integrated modeling approach to predict habitat and harvest management influences on continental-scale population responses while explicitly considering putative effects of climate change. Such a model could be readily adapted for management of many habitat-limited species.
Fecundity is fundamental to the fitness, population dynamics, conservation, and management of bir... more Fecundity is fundamental to the fitness, population dynamics, conservation, and management of birds. For all the efforts made to measure fecundity or its surrogates over the past century of avian research, it is still mismeasured, misrepresented, and misunderstood. Fundamentally, these problems arise because of partial observability of underlying processes such as renesting, multiple brooding, and temporary emigration. Over the last several decades, various analytical approaches have been developed to estimate fecundity from incomplete and biased data. These, include scalar arithmetic formulae, partial differential equations, individual-based simulations, and Markov chain methodology. In this paper, we: (1) identify component processes of avian reproduction; (2) review existing methods for modeling fecundity; (3) place these diverse models under a common conceptual framework; (4) describe the parameterization, validation, and limitations of such models; and (5) point out future considerations and challenges in the application of fecundity models. We hope this synthesis of existing literature will help direct researchers toward the most appropriate methods to assess avian reproductive success for answering questions in evolutionary ecology, natural history, population dynamics, reproductive toxicology, and management.
Fecundity is fundamental to the fitness, population dynamics, conservation, and management of bir... more Fecundity is fundamental to the fitness, population dynamics, conservation, and management of birds. For all the efforts made to measure fecundity or its surrogates over the past century of avian research, it is still mismeasured, misrepresented, and misunderstood. Fundamentally, these problems arise because of partial observability of underlying processes such as renesting, multiple brooding, and temporary emigration. Over the last several decades, various analytical approaches have been developed to estimate fecundity from incomplete and biased data. These, include scalar arithmetic formulae, partial differential equations, individual-based simulations, and Markov chain methodology. In this paper, we: (1) identify component processes of avian reproduction; (2) review existing methods for modeling fecundity; (3) place these diverse models under a common conceptual framework; (4) describe the parameterization, validation, and limitations of such models; and (5) point out future considerations and challenges in the application of fecundity models. We hope this synthesis of existing literature will help direct researchers toward the most appropriate methods to assess avian reproductive success for answering questions in evolutionary ecology, natural history, population dynamics, reproductive toxicology, and management.
Usfws Usgs Structured Decision Making Workshop National Conservation Training Center Shepherdstown Wv January 25 29 2010, Jan 25, 2010
Conservation of oceanic island species presents many ecological and logistical challenges. The No... more Conservation of oceanic island species presents many ecological and logistical challenges. The Northwestern Hawaiian Islands (NWHI) include 300,000 km 2 of ocean waters and 10 groups of sub-tropical islands and atolls of high conservation value. Designated as Papahanaumokuakea Marine National Monument, the islands provide habitat for four endangered species of terrestrial birds. Despite their protected status, many of these species are faced with the ongoing threat of extinction due to stochastic catastrophes such as disease, invasive mammal introductions, tsunamis, and hurricanes. To reduce the risk that a single catastrophe would lead to extinction, managers propose to restore multiple "insurance" populations on islands currently unoccupied by these species to increase their range and overall numbers.
1. Understanding the distribution and ecology of episodic or mobile species requires us to addres... more 1. Understanding the distribution and ecology of episodic or mobile species requires us to address multiple potential biases, including spatial clustering of survey locations, imperfect detectability and partial availability for detection. These challenges have been addressed individually by previous modelling approaches, but there is currently no extension of the occupancy modelling framework that accounts for all three problems while estimating occupancy (w), availability for detection (i.e. use; h) and detectability (P). 2. We describe a hierarchical Bayes multi-scale occupancy model that simultaneously estimates site occupancy, use, and detectability, while accounting for spatial dependence through a state-space approach based on repeated samples at multiple spatial or temporal scales. As an example application, we analyse the spatiotemporal distribution of the Louisiana waterthrush Seiurus motacilla with respect to catchment size and availability of potential prey based on data collected along Appalachian streams of southern West Virginia, USA. In spring 2009, single observers recorded detections of Louisiana waterthrush (henceforth, waterthrush) within 75 m of point-count stations (i.e. sites) during four 5-min surveys per site, with each survey broken into 1-min intervals. 3. Waterthrushes were widely distributed (w range: 0AE6-1AE0) and were regularly using (h range: 0AE4-0AE6) count circles along forested mountain streams. While accounting for detection biases and spatial dependence among nearby sampling sites, waterthrushes became more common as catchment area increased, and they became more available for detection as the per cent of the benthic macroinvertebrates that were of the orders Ephemeroptera, Plecoptera or Trichoptera (EPT) increased. These results lend some support to the hypothesis that waterthrushes are influenced by instream conditions as mediated by watershed size and benthic macroinvertebrate community composition. 4. Synthesis and applications. Although several available modelling techniques provide estimates of occupancy at one scale, hierarchical Bayes multi-scale occupancy modelling provides estimates of distribution at two scales simultaneously while accounting for detection biases and spatial dependencies. Hierarchical Bayes multi-scale occupancy models therefore hold significant potential for addressing complex conservation threats that operate at a landscape scale (e.g. climate change) and probably influence species distributions over multiple scales.
Avian monitoring is a regular component of long-term programs that evaluate changes in ecological... more Avian monitoring is a regular component of long-term programs that evaluate changes in ecological integrity following natural and anthropogenic disturbance. While bird species or guilds can serve as cost-effective indicators of such changes, accounting for imperfect detection of birds in avian monitoring programs remains a challenge. Indeed, few studies have accounted for detectability while estimating bird occupancy and abundance. We used an information-theoretic approach to model species-and guild-specifi c occupancy (ψ) and detection probabilities (p), based on bird surveys along streams in two national parks of southern West Virginia. A species-specifi c occupancy model was much more parsimonious than a guild-specifi c occupancy model, which was in turn much more parsimonious than one that assumed all species were distributed equally across the study areas. Detectability varied among guilds and species within guilds, visit occasions, observers, and stream noise levels. Even while accounting for low detectability (p < 30%), predicted occupancy was low for some species (ψ < 35%). Other species, though, had high detectability (p > 65%) and high occupancy (ψ ≥ 90%). Species with detection probabilities above 30% (to better ensure accurate occupancy estimates given our study design) represented all of the open-cup-nesting, forest-interior songbird guilds, and these are therefore good candidate indicators for a long-term monitoring program aimed at identifying annual changes in occupancy. The occupancy modeling approach provides a robust, extensible framework for long-term monitoring of individual bird species and entire communities, which can be linked to other measures of ecosystem integrity.
ABSTRACT Headwater forests serve many ecological functions and may be particularly responsive to ... more ABSTRACT Headwater forests serve many ecological functions and may be particularly responsive to changes in climate and land use. Riparian birds can serve as indicators of changes in their associated ecosystems. Little known, however, are combined influences of climate and land use on riparian birds and riparian ecosystems. We examined multiscale associations between these environmental conditions and reproduction of the Louisiana Waterthrush (Seiurus motacilla), a riparian-obligate songbird that breeds in the eastern United States. Specifically, we measured variables at multiple spatial and temporal scales to model crucial components of individual fecundity, using an information-theoretic approach. We monitored 190 nests in 139 territories within 13 drainages from 2002 to 2005. Daily nest survival reached a maximum when mean rainfall was intermediate (3–10 mm day–1) during the nesting period. Nestling survival, by contrast, reached its maximum with high amounts of rainfall (>14 ...
Louisiana Waterthrushes (waterthrushes; Seiurus motacilla) are infrequently studied Neotropical m... more Louisiana Waterthrushes (waterthrushes; Seiurus motacilla) are infrequently studied Neotropical migratory songbirds that breed throughout much of the southeastern U.S, which is undergoing rapid urbanization. They may serve as effective indicators of stream biotic integrity because of their dependence on riparian systems for food and nesting. Furthermore, waterthrushes are easier to survey than complex assemblages of fish and macroinvertebrates. While the
2015. Collaborative decision-analytic framework to maximize resilience of tidal marshes to climat... more 2015. Collaborative decision-analytic framework to maximize resilience of tidal marshes to climate change. Ecology and Society 20(1): 30. http://dx.
ABSTRACT Migratory species provide economically beneficial ecosystem services to people throughou... more ABSTRACT Migratory species provide economically beneficial ecosystem services to people throughout their range, yet often, information is lacking about the magnitude and spatial distribution of these benefits at regional scales. We conducted a case study for Northern Pintails (hereafter pintail) in which we quantified regional and sub-regional economic values of subsistence harvest to indigenous communities in Arctic and sub-Arctic North America. As a first step, we used the replacement cost method to quantify the cost of replacing pintail subsistence harvest with the most similar commercially available protein (chicken). For an estimated annual subsistence harvest of ˜15,000 pintail, our mean estimate of the total replacement cost was ˜$63,000 yr−1 ($2010 USD), with sub-regional values ranging from $263 yr−1 to $21,930 yr−1. Our results provide an order-of-magnitude, conservative estimate of one component of the regional ecosystem-service values of pintails, providing perspective on how spatially explicit values can inform migratory species conservation.
Six large-bodied, ≥ 120 g, woodpecker species are listed as near-threatened to critically endange... more Six large-bodied, ≥ 120 g, woodpecker species are listed as near-threatened to critically endangered by the International Union for Conservation of Nature (IUCN). The small population paradigm assumes that these populations are likely to become extinct without an increase in numbers, but the combined influences of initial population size and demographic rates, i.e., annual adult survival and fecundity, may drive
Coffee agroforestry systems and secondary forests have been shown to support similar bird communi... more Coffee agroforestry systems and secondary forests have been shown to support similar bird communities but comparing these habitat types are challenged by potential biases due to differences in detectability between habitats. Furthermore, seasonal dynamics may influence bird communities differently in different habitat types and therefore seasonal effects should be considered in comparisons. To address these issues, we incorporated seasonal effects and factors potentially affecting bird detectability into models to compare avian community composition and dynamics between coffee agroforests and secondary forest fragments. In particular, we modeled community composition and community dynamics of bird functional groups based on habitat type (coffee agroforest vs. secondary forest) and season while accounting for variation in capture probability (i.e. detectability). The models we used estimated capture probability to be similar between habitat types for each dietary guild, but omnivores had a lower capture probability than frugivores and insectivores. Although apparent species richness was higher in coffee agroforest than secondary forest, model results indicated that omnivores and insectivores were more common in secondary forest when accounting for heterogeneity in capture probability. Our results largely support the notion that shade-coffee can serve as a surrogate habitat for secondary forest with respect to avian communities. Small coffee agroforests embedded within the typical tropical countryside matrix of secondary forest patches and small-scale agriculture, therefore, may host avian communities that resemble those of surrounding secondary forest, and may serve as viable corridors linking patches of forest within these landscapes. This information is an important step toward effective landscape-scale conservation in Neotropical agricultural landscapes.
Understanding interactions between mobile species distributions and landcover characteristics rem... more Understanding interactions between mobile species distributions and landcover characteristics remains an outstanding challenge in ecology. Multiple factors could explain species distributions including endogenous evolutionary traits leading to conspecific clustering and endogenous habitat features that support life history requirements. Birds are a useful taxon for examining hypotheses about the relative importance of these factors among species in a community. We developed a hierarchical Bayes approach to model the relationships between bird species occupancy and local landcover variables accounting for spatial autocorrelation, species similarities, and partial observability. We fit alternative occupancy models to detections of 90 bird species observed during repeat visits to 316 point-counts forming a 400-m grid throughout the Patuxent Wildlife Research Refuge in Maryland, USA. Models with landcover variables performed significantly better than our autologistic and null models, supporting the hypothesis that local landcover heterogeneity is important as an exogenous driver for species distributions. Conspecific clustering alone was a comparatively poor descriptor of local community composition, but there was evidence for spatial autocorrelation in all species. Considerable uncertainty remains whether landcover combined with spatial autocorrelation is most parsimonious for describing bird species distributions at a local scale. Spatial structuring may be weaker at intermediate scales within which dispersal is less frequent, information flows are localized, and landcover types become spatially diversified and therefore exhibit little aggregation. Examining such hypotheses across species assemblages contributes to our understanding of community-level associations with conspecifics and landscape composition.
Rivers may serve as reservoirs for enteric organisms. Very little is known about the boundaries o... more Rivers may serve as reservoirs for enteric organisms. Very little is known about the boundaries of microbial communities in moving bodies of water so this study was undertaken to find the limits of distribution of some bacteria, focusing on enteric organisms. The presence of Salmonella, Campylobacter, and Enterococcus spp. and the antimicrobial resistance phenotypes carried by these organisms was evaluated for the Upper Oconee River basin, a small river in the lower Piedmont of northeastern Georgia, USA. Samples were obtained from 83 sites during a 3h period on a spring day (April 2005) in an approximately 30×20 km region. Campylobacter spp. was isolated at 12 sites. The Campylobacter isolates from three sites were resistant to tetracycline. Of the five short-variable region (SVR) subtypes of Campylobacter that were found, three were found at more than one site, two types were found twice, and one subtype was found three times. Enterococcus was isolated at 71 sites. E. casseliflavus was the most common species. Based on species identification and antimicrobial resistance patterns, 24 types of Enterococcus were found. Salmonella was isolated from 62 sites. Of the 19 Salmonella serovars that were isolated, serovar Muenchen accounted for about 20% of the isolates. The next three most common serovars isolated, Rubislaw, Hartford, and Give, accounted for about 44% of the river isolates. Antimicrobial resistance profiling offered limited differentiation of Salmonella isolates because only seven isolates were resistant to any antimicrobial. The sites at which Salmonella, Campylobacter, or Enterococcus were isolated did not correlate with each other or with the total coliform number or Escherichia coli count for the site. However, isolates of some of the same species and type occurred in clusters that were restricted to areas within 5 to 6 km.
The Louisiana Waterthrush (waterthrush; Seiurus motacilla) is a forest-dwelling, Nearctic-Neotrop... more The Louisiana Waterthrush (waterthrush; Seiurus motacilla) is a forest-dwelling, Nearctic-Neotropical migratory passerine that nests along streams. We attached radiotransmitters (0.6-0.8 g) to 12 nestling waterthrushes using snug, elastic loops. At three nests, adult waterthrushes were videotaped removing radio-tagged young from the nest. In addition, we recovered nine radio-backpacks (with two still attached to the carcasses of nestlings) near nests within a few days after attaching transmitters. Only one of 12 radio-tagged young was relocated more than 24 h after attaching the transmitter. Thus, the method of transmitter attachment we used was not effective. Using snug, nonelastic loops (e.g., nylon) for the harness may reduce the loss of transmitters, but may injure the skin as fledglings grow. Other possible alternatives include (1) gluing the transmitter to skin on the back of nestlings, (2) capturing fledglings in mist nets and attaching transmitters a week or more after fledging by which time contour feathers have grown and the likelihood of a parent removing the transmitter may be reduced, or (3) attempting to monitor fledglings without attaching transmitters. The success of the latter two alternatives would likely be enhanced by attaching transmitters to adults and then tracking them to locate their still-dependent fledglings.
1. Understanding the distribution and ecology of episodic or mobile species requires us to addres... more 1. Understanding the distribution and ecology of episodic or mobile species requires us to address multiple potential biases, including spatial clustering of survey locations, imperfect detectability and partial availability for detection. These challenges have been addressed individually by previous modelling approaches, but there is currently no extension of the occupancy modelling framework that accounts for all three problems while estimating occupancy (w), availability for detection (i.e. use; h) and detectability (P). 2. We describe a hierarchical Bayes multi-scale occupancy model that simultaneously estimates site occupancy, use, and detectability, while accounting for spatial dependence through a state-space approach based on repeated samples at multiple spatial or temporal scales. As an example application, we analyse the spatiotemporal distribution of the Louisiana waterthrush Seiurus motacilla with respect to catchment size and availability of potential prey based on data collected along Appalachian streams of southern West Virginia, USA. In spring 2009, single observers recorded detections of Louisiana waterthrush (henceforth, waterthrush) within 75 m of point-count stations (i.e. sites) during four 5-min surveys per site, with each survey broken into 1-min intervals. 3. Waterthrushes were widely distributed (w range: 0AE6-1AE0) and were regularly using (h range: 0AE4-0AE6) count circles along forested mountain streams. While accounting for detection biases and spatial dependence among nearby sampling sites, waterthrushes became more common as catchment area increased, and they became more available for detection as the per cent of the benthic macroinvertebrates that were of the orders Ephemeroptera, Plecoptera or Trichoptera (EPT) increased. These results lend some support to the hypothesis that waterthrushes are influenced by instream conditions as mediated by watershed size and benthic macroinvertebrate community composition. 4. Synthesis and applications. Although several available modelling techniques provide estimates of occupancy at one scale, hierarchical Bayes multi-scale occupancy modelling provides estimates of distribution at two scales simultaneously while accounting for detection biases and spatial dependencies. Hierarchical Bayes multi-scale occupancy models therefore hold significant potential for addressing complex conservation threats that operate at a landscape scale (e.g. climate change) and probably influence species distributions over multiple scales.
1. Benthic stream animals, in particular macroinvertebrates, are good indicators of water quality... more 1. Benthic stream animals, in particular macroinvertebrates, are good indicators of water quality, but sampling can be laborious to obtain accurate indices of biotic integrity. Thus, tools for bioassessment that include measurements other than macroinvertebrates would be valuable additions to volunteer monitoring protocols. 2. We evaluated the usefulness of a stream-dependent songbird, the Louisiana waterthrush (waterthrush, Seiurus motacilla) and the Environmental Protection Agency Visual Habitat Assessment (EPA VHA) as indicators of the macrobenthos community in headwater streams of the Georgia Piedmont, U.S.A. We sampled macrobenthos, surveyed waterthrushes and measured habitat characteristics along 39 headwater reaches across 17 catchments ranging from forested to heavily urbanised or grazed by cattle. 3. Of the indicators considered, waterthrush occupancy was best for predicting relative abundances of macrobenthic taxa, while the EPA VHA was best for predicting Ephemeroptera-Plecoptera-Trichoptera (EPT) richness. Individual components of EPA VHA scores were much less useful as indicators of EPT richness and % EPT when compared with the total score. Waterthrushes were found along streams with higher % EPT, a lower Family Biotic Index (FBI) values and greater macrobenthos biomass. 4. While macroinvertebrates remain one of the most direct indicators of stream water quality, stream bird surveys and reach-scale habitat assessments can serve as cost-effective indicators of benthic macroinvertebrate communities. Using stream-dependent birds as an early warning signal for degradation of stream biotic integrity could improve the efficacy of catchment monitoring programmes in detecting and identifying perturbations within the catchment.
We developed and evaluated the performance of a metapopulation model enabling managers to examine... more We developed and evaluated the performance of a metapopulation model enabling managers to examine, for the first time, the consequences of alternative management strategies involving habitat conditions and hunting on both harvest opportunity and carrying capacity (i.e., equilibrium population size in the absence of harvest) for migratory waterfowl at a continental scale. Our focus is on the northern pintail (Anas acuta; hereafter, pintail), which serves as a useful model species to examine the potential for integrating waterfowl harvest and habitat management in North America. We developed submodel structure capturing important processes for pintail populations during breeding, fall migration, winter, and spring migration while encompassing spatial structure representing three core breeding areas and two core nonbreeding areas. A number of continental-scale predictions from our baseline parameterization (e.g., carrying capacity of 5.5 million, equilibrium population size of 2.9 million and harvest rate of 12% at maximum sustained yield [MSY]) were within 10% of those from the pintail harvest strategy under current use by the U.S. Fish and Wildlife Service. To begin investigating the interaction of harvest and habitat management, we examined equilibrium population conditions for pintail at the continental scale across a range of harvest rates while perturbing model parameters to represent: (1) a 10% increase in breeding habitat quality in the Prairie Pothole population (PR); and (2) a 10% increase in nonbreeding habitat quantity along in the Gulf Coast (GC). Based on our model and analysis, a greater increase in carrying capacity and sustainable harvest was seen when increasing a proxy for habitat quality in the Prairie Pothole population. This finding and underlying assumptions must be critically evaluated, however, before specific management recommendations can be made. To make such recommendations, we require (1) extended, refined submodels with additional parameters linking influences of habitat management and environmental conditions to key life-history parameters; (2) a formal sensitivity analysis of the revised model; (3) an integrated population model that incorporates empirical data for estimating key vital rates; and (4) cost estimates for changing these additional parameters through habitat management efforts. We foresee great utility in using an integrated modeling approach to predict habitat and harvest management influences on continental-scale population responses while explicitly considering putative effects of climate change. Such a model could be readily adapted for management of many habitat-limited species.
Fecundity is fundamental to the fitness, population dynamics, conservation, and management of bir... more Fecundity is fundamental to the fitness, population dynamics, conservation, and management of birds. For all the efforts made to measure fecundity or its surrogates over the past century of avian research, it is still mismeasured, misrepresented, and misunderstood. Fundamentally, these problems arise because of partial observability of underlying processes such as renesting, multiple brooding, and temporary emigration. Over the last several decades, various analytical approaches have been developed to estimate fecundity from incomplete and biased data. These, include scalar arithmetic formulae, partial differential equations, individual-based simulations, and Markov chain methodology. In this paper, we: (1) identify component processes of avian reproduction; (2) review existing methods for modeling fecundity; (3) place these diverse models under a common conceptual framework; (4) describe the parameterization, validation, and limitations of such models; and (5) point out future considerations and challenges in the application of fecundity models. We hope this synthesis of existing literature will help direct researchers toward the most appropriate methods to assess avian reproductive success for answering questions in evolutionary ecology, natural history, population dynamics, reproductive toxicology, and management.
Uploads
Papers by Brady Mattsson