How do en route events around the Gulf of Mexico influence migratory landbird populations?

Cohen, Emily B.; Barrow, Wylie C.; Buler, Jeffrey J.; Deppe, Jill L.; Farnsworth, Andrew; Marra, Peter P.; McWilliams, Scott R.; Mehlman, David W.; Wilson, Ryan R.; Woodrey, Mark S.; Moore, Frank R.

doi:10.1650/condor-17-20.1

Cited by 48 publications

(53 citation statements)

References 142 publications

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“…Generating these estimates required a series of advances in radar processing and analytical methods (e.g., big data analytics for the entire radar archive), species occurrence information (eBird) and distribution modeling techniques (STEM), and in the procedures for calculating bird number through the integration of these resources and methods. The characterization presented in this study represents a major leap forward for understanding the magnitude of bird migration in the Gulf region and brings us closer to achieving critical goals of monitoring in the region and understanding the role of migration in the dynamics of bird populations (Cohen et al, ). Our results from 2007 to 2015 did not show evidence of an overall decline in the number of migrating birds, however we did see evidence of a decline in the eastern Gulf.…”

Section: Discussionmentioning

confidence: 99%

Holding steady: Little change in intensity or timing of bird migration over the Gulf of Mexico

Horton

Doren

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et al. 2019

Global Change Biology

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Quantifying the timing and intensity of migratory movements is imperative for understanding impacts of changing landscapes and climates on migratory bird populations. Billions of birds migrate in the Western Hemisphere, but accurately estimating the population size of one migratory species, let alone hundreds, presents numerous obstacles. Here, we quantify the timing, intensity, and distribution of bird migration through one of the largest migration corridors in the Western Hemisphere, the Gulf of Mexico (the Gulf). We further assess whether there have been changes in migration timing or intensity through the Gulf. To achieve this, we integrate citizen science (eBird) observations with 21 years of weather surveillance radar data (1995–2015). We predicted no change in migration timing and a decline in migration intensity across the time series. We estimate that an average of 2.1 billion birds pass through this region each spring en route to Nearctic breeding grounds. Annually, half of these individuals pass through the region in just 18 days, between April 19 and May 7. The western region of the Gulf showed a mean rate of passage 5.4 times higher than the central and eastern regions. We did not detect an overall change in the annual numbers of migrants (2007–2015) or the annual timing of peak migration (1995–2015). However, we found that the earliest seasonal movements through the region occurred significantly earlier over time (1.6 days decade−1). Additionally, body mass and migration distance explained the magnitude of phenological changes, with the most rapid advances occurring with an assemblage of larger‐bodied shorter‐distance migrants. Our results provide baseline information that can be used to advance our understanding of the developing implications of climate change, urbanization, and energy development for migratory bird populations in North America.

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Section: Discussionmentioning

confidence: 99%

Holding steady: Little change in intensity or timing of bird migration over the Gulf of Mexico

Horton

Doren

Sorte

et al. 2019

Global Change Biology

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“…An optimal migration strategy should minimize distance, time, and predation risk and/or maximize arrival condition (Alerstam 2011). suitable habitat; Buler et al 2007, Cohen et al 2017. However, migration routes and timing are also influenced by exogenous factors encountered en route such as weather conditions and distributions of resources (e.g.…”

Section: Introductionmentioning

confidence: 99%

The strength of migratory connectivity for birds en route to breeding through the Gulf of Mexico

et al. 2018

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The strength of migratory connectivity is a measure of the cohesion of populations among phases of the annual cycle, including breeding, migration, and wintering. Many Nearctic-Neotropical species have strong migratory connectivity between breeding and wintering phases of the annual cycle. It is less clear if this strength persists during migration when multiple endogenous and exogenous factors may decrease the cohesion of populations among routes or through time along the same routes. We sampled three bird species, American redstart Setophaga ruticilla, ovenbird Seiurus aurocapilla, and wood thrush Hylocichla mustelina, during spring migration through the Gulf of Mexico region to test if breeding populations differentiate spatially among migration routes or temporally along the same migration routes and the extent to which withinpopulation timing is a function of sex, age, and carry-over from winter habitat, as measured by stable carbon isotope values in claws (δ 13 C). To make quantitative comparisons of migratory connectivity possible, we developed and used new methodology to estimate the strength of migratory connectivity (MC) from probabilistic origin assignments identified using stable hydrogen isotopes in feathers (δ 2 H). We found support for spatial differentiation among routes by American redstarts and ovenbirds and temporal differentiation along routes by American redstarts. After controlling for breeding origin, the timing of American redstart migration differed among ages and sexes and ovenbird migration timing was influenced by carry-over from winter habitat. The strength of migratory connectivity did not differ among the three species, with each showing weak breeding-to-spring migration MC relative to prior assessments of breeding-wintering connectivity. Our work begins to fill an essential gap in methodology and understanding of the extent to which populations remain together during migration, information critical for a full annual cycle perspective on the population dynamics and conservation of migratory animals.

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“…Migrants can assess favourable migration conditions ahead as is evident in predictable mass movements of migrants, e.g. autumn migrants departed over the Gulf of Mexico with the passage of strong cold fronts (Cohen et al 2017).…”

Section: B What Is the Influence Of (Seasonally Changing) Weather Comentioning

confidence: 99%

The grand challenges of migration ecology that radar aeroecology can help answer

et al. 2018

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Many migratory species have experienced substantial declines that resulted from rapid and massive expansions of human structures and activities, habitat alterations and climate change. Migrants are also recognized as an integral component of biodiversity and provide a multitude of services and disservices that are relevant to human agriculture, economy and health. The plethora of recently published studies reflects the need for better fundamental knowledge on migrations and for better management of their ecological and human‐relevant effects. Yet, where are we in providing answers to fundamental questions and societal challenges? Engaging a broad network of researchers worldwide, we used a horizon‐scan approach to identify the most important challenges which need to be overcome in order to gain a fuller understanding of migration ecology, and which could be addressed using radar aeroecological and macroecological approaches. The top challenges include both long‐standing and novel topics, ranging from fundamental information on migration routes and phenology, orientation and navigation strategies, and the multitude of effects migrants may have on resident communities, to societal challenges, such as protecting or preventing migrant services and disservices, and the conservation of migrants in the face of environmental changes. We outline these challenges, identify the urgency of addressing them and the primary stakeholders – researchers, policy makers and practitioners, or funders of research.

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How do en route events around the Gulf of Mexico influence migratory landbird populations?

Cited by 48 publications

References 142 publications

Holding steady: Little change in intensity or timing of bird migration over the Gulf of Mexico

Holding steady: Little change in intensity or timing of bird migration over the Gulf of Mexico

The strength of migratory connectivity for birds en route to breeding through the Gulf of Mexico

The grand challenges of migration ecology that radar aeroecology can help answer

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