Long Term Studies

Many studies have reported statistically significant associations between bird migratory phenology and climatic variables, and, consequently, it is mostly accepted that recent shifts in migration dates are a reaction to present climate change. Impacts of weather and climate on departure date, progression and stopover frequency and duration have been reviewed in order to explain the current knowledge of climatic mechanisms underlying such phenological shifts. Climate in departure areas can affect population phenology via the size of the returning population. In a short-term sense, ecological conditions can affect acquisition of migratory body condition during the days preceding departure. Migratory phenology can also be affected by quality and quantity of replaced feathers during moult. Adverse weather conditions en route strongly hinder the progression of individuals and even force them to land. The time spent on stopovers will greatly depend on the ecological conditions there and the opportunities for refuelling. Temperature is by far the climatic variable most frequently related to avian phenology. The use of climatic indices is spreading because they have the advantage of synthesizing weather conditions into a single variable. Remote sensing is probably the best option to explore ecological conditions in areas used by migratory species. Most of the climatic variables employed are from the arrival area, while climate from passage or departure areas is rarely assessed. The overwhelming majority of studies have used variables defined by months, while the use of periods designed ad hoc according to species’ biology is almost anecdotal. It can be concluded that further research is needed to disentangle the true relevance of each type of climatic variable over avian migratory phenology during each phase of migration.

The recent trend for journals to require open access to primary data included in publications has been embraced by many biologists, but has caused apprehension amongst researchers engaged in long-term ecological and evolutionary studies. A worldwide survey of 73 principal investigators (Pls) with long-term studies revealed positive attitudes towards sharing data with the agreement or involvement of the PI, and 93% of PIs have historically shared data. Only 8% were in favor of uncontrolled, open access to primary data while 63% expressed serious concern. We present here their viewpoint on an issue that can have non-trivial scientific consequences. We discuss potential costs of public data archiving and provide possible solutions to meet the needs of journals and researchers.

Plant phenology is strongly controlled by climate and has consequently become one of the most reliable bioindicators of ongoing climate change. We used a dataset of more than 200 000 records for six phenological events of 29 perennial plant species monitored from 1943 to 2003 for a comprehensive assessment of plant phenological responses to climate change in the Mediterranean region. Temperature, precipitation and North Atlantic Oscillation (NAO) were studied together during a complete annual cycle before phenological events to determine their relative importance and potential seasonal carry‐over effects. Warm and dry springs under a positive phase of NAO advance flowering, leaf unfolding and fruiting dates and lengthen the growing season. Spatial variability of dates (range among sites) was also reduced during warm and dry years, especially for spring events. Climate during previous weeks to phenophases occurrence had the greatest impact on plants, although all events were also affected by climate conditions several months before. Immediate along with delayed climate effects suggest dual triggers in plant phenology. Climatic models accounted for more than 80% of variability in flowering and leaf unfolding dates, and in length of the growing season, but for lower proportions in fruiting and leaf falling. Most part of year‐to‐year changes in dates was accounted for temperature, while precipitation and NAO accounted for <10% of dates' variability. In the case of flowering, insect‐pollinated species were better modelled by climate than wind‐pollinated species. Differences in temporal responses of plant phenology to recent climate change are due to differences in the sensitivity to climate among events and species. Spring events are changing more than autumn events as they are more sensitive to climate and are also undergoing the greatest alterations of climate relative to other seasons. In conclusion, climate change has shifted plant phenology in the Mediterranean region.

The recent trend for journals to require open access to primary data included in publications has been embraced by many biologists, but has caused apprehension amongst researchers engaged in long-term ecological and evolutionary studies. A worldwide survey of 73 principal investigators (Pls) with long-term studies revealed positive attitudes towards sharing data with the agreement or involvement of the PI, and 93% of PIs have historically shared data. Only 8% were in favor of uncontrolled, open access to primary data while 63% expressed serious concern. We present here their viewpoint on an issue that can have non-trivial scientific consequences. We discuss potential costs of public data archiving and provide possible solutions to meet the needs of journals and researchers.

• La llegada primaveral de las aves migratorias se ha adelantado desde mediados de los 70 en torno a una semana, si bien las fechas actuales son similares a las que ya se registraban en los años 40.
• La fecha en que las aves abandonan nuestro país en otoño ha fluctuado a lo largo de las últimas seis décadas, pareciendo existir una cierta tendencia a irse antes en los últimos años.
• La fenología migratoria depende de las temperaturas en España en los periodos migratorios y, en el caso de la migración primaveral, además de las condiciones acaecidas durante todo el invierno en sus cuarteles de invierno.
• Los años calurosos favorecen una llegada más temprana, pero la sequía en África la retrasa.

Long-term studies are those studies with a longer duration than usual in its topic. They have been essential in ecology to understand the ecological processes that happen in long temporal scales, to determine how general is a pattern emerging from a punctual finding, and to connect cause and effect in biological processes happening with some time lag. Most of ecologists agree about the scientific relevance of long-term studies, but they seldom carry out them (0.3% of published studies). The main handicap is to keep continuous funding during a long time because funding and evaluation system of science is based on short periods. However, there are opportunities to develop long-term studies with available data yet, such as monitoring programs of protected areas or threatened species, museum collections, hunting bags, fisheries or citizen sciences projects; although we will need to keep in mind that those data were not gathered with a long-term aim and this fact may constrain soundness of our conclusions. In spite of the fact that behavioral ecology is a young discipline in Spain, there are already some notable examples of long-term studies. For instance, it has been demonstrated that birds and insects are changing their life cycles in response to climate change and these changes can be leading to phenological mismatchings with the trophic levels in which they rely on. Marking and monitoring of the same individuals along years in the host-parasite system of magpies and cuckoos demonstrated that magpies learn to protect themselves against parasites, while have an inflexible reproductive phenology unable to adapt to environmental variation. Individual-based monitoring of black kites showed the effect of senescence and learning in migratory behavior, breeding territory acquisition, and fitness changes along the life of these birds. Similar results were found for other long-lived birds such as white storks, gulls or storm petrels. Individual marking has allowed building complete pedigrees in bird populations using nest boxes for breeding. Such pedigrees have been essential to understand heritability of several coloration traits of plumage directly linked to the phenotypic individual quality.

Keywords: animal models; individual-based monitoring; microevolution; phenotypic plasticity; replication; temporal trends.

The impact of climate change on the bird communities of Asia is poorly understood. Since the 1950s, the Japanese Meteorology Agency has recorded first arrival (i.e. first sighting) and first singing for a selection of resident (Alauda arvensis, Cettia diphone, and Lanius bucephalus) and migratory species (Hirundo rustica and Cuculus canorus) in more than 300 bird populations. First records (i.e. first sighting or singing) show a delay of 5.4 d since the end of the 1970s. Nevertheless, there is a marked heterogeneity in the temporal trends among populations in each species. Most populations of A. arvensis, C. diphone and H. rustica show a negative relationship with local temperature (i.e. first records were earlier in warmer years) and this sensitivity to temperatures has increased in recent decades. Exploration of the possible causes of variability in phenological trends among populations demonstrated that greater delays were observed in those populations subjected to smaller increases in local temperature and a greater increase in human population (a surrogate for the conservation status of bird populations). Therefore, declining bird populations are the most probable cause of the observed delay in the phenology of first individuals. Migratory species were affected by climate in their wintering and passage areas. Overall, first sightings of H. rustica were earlier, while the onset of singing by C. canorus was delayed in response to warmer temperatures in southeastern Asia. However, there was a noteworthy variability among populations, with no discernable regionalization or spatial organization. This suggests that there is no clear connectivity between breeding and wintering populations.

KEY WORDS: Arrival date · Heat island effect · Long-term study · Migratory birds · Phenology · Singing onset · Temperature · Warming

There is irrefutable evidence that spring phenology of birds, such as the timing of migration and reproduction, is advancing in response to ongoing climate change. However, most of the species and populations have been studied in temperate and northern latitudes, where annual seasonality of temperatures is stronger. Here, singing onset phenology in eight populations of the endemic Japanese bush warbler Cettia diphone riukiuensis from the subtropical Ryukyu and Sakishima Islands (24.3–28.4°N) has been studied for the period 1953–2005. Overall, males are singing 13 days later during the last five decades. Temperature increased in the study sites during the study period and most populations showed a negative effect of temperature before singing season. This apparently contradictory phenological response to climate change may be another evidence of the population declines detected in the endemic species of the small southern islands of Japan as a result of habitat loss and degradation. Patterns in the variability among the studied insular populations further confirmed this hypothesis. Those populations showing the strongest delays were those undergoing the higher increase of human population in their islands. However, this effect was strongly influenced by the island area. Phenology of birds in the smallest islands showed the smallest dependence on temperature, and consequently these populations are unable to adapt their responses to rising temperatures. This relationship is probably mediated by the poor genetic variability expected in the small insular populations. These results suggest that insular populations could be threatened by climate change besides particular threats at local scale suffered by each population.

The recent trend for journals to require open access to primary data included in publications has been embraced by many biologists, but has caused apprehension amongst researchers engaged in long-term ecological and evolutionary studies. A worldwide survey of 73 principal investigators (Pls) with long-term studies revealed positive attitudes towards sharing data with the agreement or involvement of the PI, and 93% of PIs have historically shared data. Only 8% were in favor of uncontrolled, open access to primary data while 63% expressed serious concern. We present here their viewpoint on an issue that can have non-trivial scientific consequences. We discuss potential costs of public data archiving and provide possible solutions to meet the needs of journals and researchers.