High spatiotemporal overlap in the non‐breeding season despite geographically dispersed breeding locations in the eastern whip‐poor‐will (<i>Antrostomus vociferus</i>)

Skinner, Aaron A.; Ward, Michael P.; Souza‐Cole, Ian; Wright, James R.; Thompson, Frank R.; Benson, Thomas J.; Matthews, Stephen N.; Tonra, Christopher M.

doi:10.1111/ddi.13477

Cited by 10 publications

(11 citation statements)

References 88 publications

(184 reference statements)

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“…Nightjars returned to the same breeding and wintering locations in subsequent years, where mean differences of a few hundred meters may reflect individual between-year adjustments influenced by ecological factors such as habitat configuration and competition (Jackson 2003, Camacho 2014, Stevens et al 2017. The strong winter site-fidelity documented here conforms with resent reports on the Eastern Whip-poor-will (Antrstomus vociferus ), a New World long-distance migrating nightjar (Bakermans et al 2022, Skinner et al 2022. Nightjars rely on their cryptic plumage when they perch motionless in daylight and survival probability is likely habitat dependent (Camacho 2014, Stevens et al 2017.…”

Section: Consistent Winter Space-usesupporting

confidence: 78%

The spatial consistency of migratory route and stopover choice in European nightjars quantified by nearest neighbour analysis on multi-annual GPS tracks

Norevik¹,

Åkesson²,

Hedenström

2022

Preprint

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The degree to which avian migrants return to the same stationary sites to mimic routes from previous years has received more and more attention as the possibility of tracking small to medium avian migrants over multiple annual cycles has increased. Repeated measurements of individuals can potentially inform about their navigation and migration strategies and to what extent the degree of variation observed within and among individuals may reflect the selective potential in the population. Here we perform a k-nearest neighbour analysis along with a repeatability measure to distinguish events in the annual cycle with intra-individual spatial convergence and to quantify the degree of individual consistency and repeatability at those events. To demonstrate the usefulness of our approach we analyse the annual space-use of European nightjars (henceforth nightjars) Caprimulgus europaeus tracked in multiple years between northern Europe and southern Africa. We found that the nightjars consistently used the same breeding and wintering sites but that individual route choice during migration were flexible, but significantly repeatable relative to population level variation during the Sahara-crossing. Thus, the nightjars followed individual-specific flyways while allowing for variation of a few hundred kilometres in the actual route in both autumn and spring. The exception was a strong within-individual convergence down to a few tens of kilometres recorded at the initiation of the trans-Saharan flight in spring. Our results suggest that nightjars have incorporated an individual-specific space-use within their annual cycle, but that they allow for a state-dependent flexibility possibly driven by the cost-benefit balance between the use of known stationary sites and an economical route-choice.

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Section: Consistent Winter Space-usesupporting

confidence: 78%

The spatial consistency of migratory route and stopover choice in European nightjars quantified by nearest neighbour analysis on multi-annual GPS tracks

Norevik¹,

Åkesson²,

Hedenström

2022

Preprint

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“…Thus, Caprimulgids may rely more on behavioral approaches to maintain thermoregulatory and metabolic equilibrium in the non-breeding season. Third, all three Caprimulgids studied here had low migratory connectivity, such that birds from across large breeding ranges converge on core wintering areas (Norevik et al ., 2020; Knight et al ., 2021; Korpach et al ., 2022; Skinner et al ., 2022b). We expect winter environmental conditions to be fairly uniform in species with low migratory connectivity, although birds could select wintering locations at smaller spatial scales to provide more favorable environmental conditions for their given body size (especially if wintering in mountainous areas).…”

Section: Discussionmentioning

confidence: 99%

“…Location data from the Argos-GPS tags on nighthawks was transmitted remotely via the Argos satellite system. See the following references for details relevant to deployment methods for each species (Knight et al ., 2021 for nighthawks; Bakermans et al ., 2022; Korpach et al ., 2022; and Skinner et al ., 2022b for whip-poor-wills; Lathouwers et al ., 2022; and Norevik et al ., 2019 for European nightjars).…”

Section: Methodsmentioning

confidence: 99%

“…If an individual was captured during multiple years, we discarded data from when individuals were juveniles, and averaged morphological data from all adult capture occasions. All individuals tracked across multiple years in our study wintered within a few hundred meters of previous years (16/16 of whip-poor-will, 7/7 European nightjars; Bakermans et al, 2022;Norevik et al, 2022a;Skinner et al, 2022b;Korpach et al, in prep), thus we used the winter location from the first year available. The majority of individuals caught across years on the breeding grounds were captured in the same location, and all individuals were captured within 2 km of the original capture location (Ng et al, 2018;Norevik et al, 2022a).…”

Section: Breeding and Wintering Location Identificationmentioning

confidence: 99%

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Assessing an age-old ecogeographical rule in nightjars across the full annual cycle

Skinner,

Korpach,

Åkesson

et al. 2023

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Bergmann’s rule states that homeotherms are larger in colder climates (which occur at higher latitudes and elevations) due to thermoregulatory mechanisms. Despite being perhaps the most extensively studied biogeographical rule across all organisms, consistent mechanisms explaining which species or taxa adhere to Bergmann’s rule have been elusive. Furthermore, evidence for Bergmann’s rule in migratory animals has been mixed, and it was difficult to assess how environmental conditions across the full annual cycle impact body size until the recent miniaturization of tracking technology. Nightjars (Family Caprimulgidae), nocturnal birds with physiological and behavioral adaptations (e.g., torpor) to cope with the environmental extremes they often experience, offer a unique opportunity to elucidate the mechanisms underpinning Bergmann’s rule. Many nightjar species are strongly migratory and have large breeding ranges, offering the opportunity to look at variation in potential drivers within and across seasons of the annual cycle. Furthermore, variation in migration strategy within the family provides an opportunity to separate adaptations for migration strategy from adaptations for thermal tolerance. In this study, we use cross-continental data from three species of nightjars (Common nighthawk, Eastern whip-poor-will, and European nightjar) to assess 1) whether migratory species in this clade adheres to Bergmann’s rule, 2) which environmental factors are the best predictors of body size, and 3) the extent to which environmental conditions across the full annual cycle determine body size. For each species, we use breeding and winter location data from GPS tags to compare competing hypotheses explaining variation in body size: temperature regulation, productivity, and seasonality (during both the breeding and wintering periods), and migration distance. We found that Common nighthawk and Eastern whip-poor-will exhibit Bergmannian patterns in body size while European nightjar does not, although the spread of tag deployment sites on the breeding grounds was minimal for the European nightjar. Predictor variables associated with nightjar breeding locations more often explained body size than did variables on the wintering grounds. Surprisingly, models representing the geography hypothesis were best represented among important models in our final data set. Latitude and longitude correlated strongly with environmental variables and migratory distance; thus, these geographical variables offer a composite variable of sorts, summarizing many factors that likely influence body size in nightjars. Leveraging multi-species and cross-continental data across the full annual cycle, along with global environmental data, can provide insight into long-standing questions and will be important for understanding the generalizability of Bergmann’s rule.

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“…Quantifying the linkages among breeding and non-breeding regions can allow researchers to infer connections between demographic trends observed on the breeding ground and conditions on the non-breeding ground [6][7][8][9]. Despite its importance, migratory connectivity is rarely investigated and existing accounts are often derived from sampling that is limited in its spatial or temporal scale (but see [10][11][12]). For example, connectivity studies based on band recoveries are frequently based on only two locations per individual: a single location from the breeding ground and a single location from the nonbreeding season [13,14].…”

Section: Introductionmentioning

confidence: 99%

Spatial and temporal scale-dependence of the strength of migratory connectivity in a North American passerine

Sharp

Rushing

Contina

et al. 2022

Preprint

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Background Migratory connectivity describes the extent to which portions of a migratory population that are spatially associated during one stage of the annual cycle remain associated during other stages of the annual cycle. The strength of migratory connectivity may vary spatially across a species’ range and temporally as individuals move through stages of their annual cycle. Few studies have quantified this spatial and temporal variation in the strength of migratory connectivity within a single species. Methods We investigated spatial and temporal variation in the strength of migratory connectivity in Painted Buntings (Passerina ciris), a small migratory bird that, uniquely among North American songbirds, breeds in disjunct eastern and western populations. Using tracking data from 113 individuals sampled at eleven breeding sites across the species’ breeding distribution, we quantified the strength of connectivity at multiple spatial and temporal scales. Results We found strong breeding-to-winter connectivity at the range-wide scale, with interior and eastern Painted Buntings remaining separate throughout the annual cycle, but weak connectivity within populations, with individuals from different regions of both populations mixing extensively on the wintering ground. Despite weak breeding-to-winter connectivity within populations, the interior population displayed strong breeding-to-molting connectivity, with birds from different breeding sites showing distinct migratory strategies during the molting period. Conclusion These results demonstrate the extent to which the strength of migratory connectivity can vary across both space and time within a single species and underscore the importance of careful sampling design when quantifying this metric. Because inferences about the strength of connectivity can be sensitive to when and where sampling occurs, there is an urgent need for continued focus on study design regarding migratory connectivity.

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High spatiotemporal overlap in the non‐breeding season despite geographically dispersed breeding locations in the eastern whip‐poor‐will (Antrostomus vociferus)

Abstract: This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 10 publications

References 88 publications

The spatial consistency of migratory route and stopover choice in European nightjars quantified by nearest neighbour analysis on multi-annual GPS tracks

The spatial consistency of migratory route and stopover choice in European nightjars quantified by nearest neighbour analysis on multi-annual GPS tracks

Assessing an age-old ecogeographical rule in nightjars across the full annual cycle

Spatial and temporal scale-dependence of the strength of migratory connectivity in a North American passerine

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