Long-term phenological shifts in migration and breeding-area residency in eastern North American raptors

Therrien, Jean‐François; Lecomte, Nicolas; Zgirski, Thomas; Jaffré, Mikaël; Beardsell, Andréanne; Goodrich, Laurie J.; Bêty, Joël; Franke, Alastair; Zlonis, Edmund J.; Bildstein, Keith L.

doi:10.1642/auk-17-5.1

Cited by 22 publications

(26 citation statements)

References 42 publications

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“…As the NAO has nevertheless also been frequently suggested to be related to autumn migration phenology (e.g. Calvert et al, and Therrien et al, ; see Introduction and Appendix S1), we also performed a time window analysis of daily NAO indices. The daily NAO data were downloaded from the website of the Climate Prediction Center of the National Oceanic and Atmospheric Administration (http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.shtml).…”

Section: Methodsmentioning

confidence: 99%

Autumn bird migration phenology: A potpourri of wind, precipitation and temperature effects

Haest

Hüppop

Pol

et al. 2019

Global Change Biology

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Climate change has caused a clear and univocal trend towards advancement in spring phenology. Changes in autumn phenology are much more diverse, with advancement, delays, and 'no change' all occurring frequently. For migratory birds, patterns in autumn migration phenology trends have been identified based on ecological and life-history traits. Explaining interspecific variation has nevertheless been challenging, and the underlying mechanisms have remained elusive. Radar studies on nonspecies-specific autumn migration intensity have repeatedly suggested that there are strong links with weather. In long-term species-specific studies, the variance in autumn migration phenology explained by weather has, nevertheless, been rather low, or a relationship was even lacking entirely. We performed a spatially explicit time window analysis of weather effects on mean autumn passage of four trans-Saharan and six intra-European passerines to gain insights into this apparent contradiction.We analysed data from standardized daily captures at the Heligoland island constanteffort site (Germany), in combination with gridded daily temperature, precipitation and wind data over a 55-year period (1960-2014), across northern Europe. Weather variables at the breeding and stopover grounds explained up to 80% of the speciesspecific interannual variability in autumn passage. Overall, wind conditions were most important. For intra-European migrants, wind was even twice as important as either temperature or precipitation, and the pattern also held in terms of relative contributions of each climate variable to the temporal trends in autumn phenology.For the trans-Saharan migrants, however, the pattern of relative trend contributions was completely reversed. Temperature and precipitation had strong trend contributions, while wind conditions had only a minor impact because they did not show any strong temporal trends. As such, understanding species-specific effects of climate on autumn phenology not only provides unique insights into each species' ecology but also how these effects shape the observed interspecific heterogeneity in autumn phenological trends. K E Y W O R D S bird migration, environmental plasticity, fall, Helgoland, radar, rainfall, spatiotemporal analysis, time window analysis | 4065 HAEST ET Al.

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Section: Methodsmentioning

confidence: 99%

Autumn bird migration phenology: A potpourri of wind, precipitation and temperature effects

Haest

Hüppop

Pol

et al. 2019

Global Change Biology

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“…Phenological changes due to climate warming, in particular the earlier onset of spring, have received much attention because of a high incidence of asynchrony across trophic levels (Kharouba et al, 2018), where mismatches may have population and evolutionary consequences (Visser & Gienapp, 2019), and potentially disrupt the function, persistence and resilience of ecosystems (Thackeray et al, 2010). In contrast, the effects of delays in the onset of autumn remain understudied (Gallinat et al, 2015), despite their potential importance for population dynamics in a wide range of species (mammalian herbivores: Hurley et al, 2014; insect herbivores: Ekholm et al, 2019; birds: Therrien et al, 2017; bears: Hertel et al, 2018) and ecosystem processes (Piao et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

The neglected season: Warmer autumns counteract harsher winters and promote population growth in Arctic reindeer

Loe

Liston

Pigeon

et al. 2020

Global Change Biology

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Arctic ungulates are experiencing the most rapid climate warming on Earth. While concerns have been raised that more frequent icing events may cause die‐offs, and earlier springs may generate a trophic mismatch in phenology, the effects of warming autumns have been largely neglected. We used 25 years of individual‐based data from a growing population of wild Svalbard reindeer, to test how warmer autumns enhance population growth. Delayed plant senescence had no effect, but a six‐week delay in snow‐onset (the observed data range) was estimated to increase late winter body mass by 10%. Because average late winter body mass explains 90% of the variation in population growth rates, such a delay in winter‐onset would enable a population growth of r = 0.20, sufficient to counteract all but the most extreme icing events. This study provides novel mechanistic insights into the consequences of climate change for Arctic herbivores, highlighting the positive impact of warming autumns on population viability, offsetting the impacts of harsher winters. Thus, the future for Arctic herbivores facing climate change may be brighter than the prevailing view.

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“…Dietary diversity represents the dietary diversity index provided by Therrien et al. (2017). Habitat types is the number of “level 2” habitat types occupied during the breeding season (BirdLife International, 2020).…”

Section: Resultsmentioning

confidence: 99%

“…We included three traits that we treated as continuous variables (size, diet and habitat specialization) and two traits we treated as categorical variables (migratory behaviour and DDT susceptibility). For the three continuous variables, we obtained species‐specific values for the average body mass of adults (Ferguson‐Lees & Christie, 2001), diet diversity index (Therrien et al., 2017) and the number of “level 2” habitat types occupied during the breeding season ( sensu BirdLife International, 2020). We described species based on their migratory behaviour as either a complete or a partial migrant (Supporting Information Appendix S1, Methods and Table S1).…”

Section: Methodsmentioning

confidence: 99%

Shared functional traits explain synchronous changes in long‐term count trends of migratory raptors

Dumandan

Bildstein

Goodrich

et al. 2020

Global Ecol. Biogeogr.

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Aim Assessing long‐term shifts in faunal assemblages is important to understand the consequences of ongoing global environmental change. One approach to assess drivers of assemblage changes is to identify the traits associated with synchronous shifts in count trends among species. Our research identified traits influencing trends in 73 years of count data on migrating raptors recorded in the north‐eastern USA. Location Pennsylvania, USA. Time period 1946–2018. Major taxa studied Birds of prey/raptors. Methods Migrating raptors were counted during autumn, following a standardized protocol. We used a hierarchical breakpoint model to identify when count trends shifted and to assess the role of traits in driving these trends before and after the breakpoint. Specifically, we quantified the probability of the direction (PD) of an effect of body mass, habitat or dietary specialization, migratory behaviour and susceptibility to dichlorodiphenyltrichloroethane (DDT) on count trends. Results We documented an assemblage‐wide mean shift in count trends of migrating raptors in 1974. In general, species that exhibited negative count trends before the breakpoint exhibited positive count trends afterwards. We found that traits associated with resource use (diet and habitat specialization) had high probabilities of affecting count trends, pre‐ and post‐breakpoint (> 90%). Moreover, the direction of their effects differed during both periods. Unexpectedly, other traits we evaluated, including DDT susceptibility, had relatively weaker associations with count trends. Main conclusions Trait‐based frameworks have promise for testing generalized assumptions about drivers of population trajectories. Historically, DDT was considered a key driver of changes in raptor population trends. However, our analysis suggests that other factors were also relevant. Moreover, the positive association between count trends and generalist behaviour depended on the temporal context. This result has implications for other settings where demographic trends can be linked to traits and help to identify drivers of biodiversity change.

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Long-term phenological shifts in migration and breeding-area residency in eastern North American raptors

Cited by 22 publications

References 42 publications

Autumn bird migration phenology: A potpourri of wind, precipitation and temperature effects

Autumn bird migration phenology: A potpourri of wind, precipitation and temperature effects

The neglected season: Warmer autumns counteract harsher winters and promote population growth in Arctic reindeer

Shared functional traits explain synchronous changes in long‐term count trends of migratory raptors

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