Niche dynamics suggest ecological factors influencing migration in an insectivorous owl

Abstract

Seasonal migration is a widespread phenomenon undertaken by myriad organisms, including birds. Competing hypotheses about ultimate drivers of seasonal migration in birds contrast relative resource abundances at high latitudes (“southern home hypothesis”) against avoidance of winter resource scarcity (“dispersal‐migration hypothesis”). However, direct tests of these competing hypotheses have been rare and to date limited to historical biogeographic reconstructions. Here we derive novel predictions about the dynamics of individual niches from each hypothesis and provide a framework for evaluating support for these competing hypotheses using contemporary environmental and behavioral data. Using flammulated owls (Psiloscops flammeolus) as a model, we characterized year‐round occupied niche dynamics using high‐resolution global positioning system tracking and remote‐sensed environmental data. We also compared occupied niche dynamics to counterfactual niches using simulated alternative nonmigratory strategies. Owl occupied mean niche was conserved among seasons, whereas niche variance was generally higher during migratory periods. Simulated year‐round residents in Mexico would have experienced putatively more productive niches than migrants. These findings provide ecological support for the “dispersal‐migration” hypothesis in which winter resource scarcity is the primary driver of migration rather than summer resource abundances.

Seasonal migration alters energetic trade‐off optimization and shapes life history

“…The net energy benefit of migration increased with seasonality of the breeding location and migratory distance, implying that the emergence of a long-distance migration from high-latitude residents is associated with a large increase in reproductive potential that far exceeds the best-performing stationary solution. Recent work has suggested a high-latitude origin for most avian migrations as opposed to earlier theories which posit a 'southern home' (Bruderer & Salewski, 2008;Winger et al, 2011Winger et al, , 2019Yanco et al, 2021). Our results provide theoretical justification for these observations in showing large realized fitness benefits of migration as compared to otherwise optimized non-migratory strategies.…”

“…Seasonal migration is a behaviour with putatively substantial effects on POL but empirical findings about the direction and magnitude of those effects vary depending on the taxonomic scale of comparison, environmental context and characterization of the behaviour (Soriano-Redondo et al, 2020;Winger & Pegan, 2021). Migration radically alters the environmental conditions an organism experiences, typically leading to niche tracking, maintaining relatively invariant conditions across the annual cycle (Abrahms et al, 2021;Alerstam et al, 2019;Gómez et al, 2016;Merkle et al, 2016;Nakazawa et al, 2004;Thorup et al, 2017;Yanco et al, 2021;Zurell et al, 2018), which might be expected to favour a slow POL. On the other hand, migration is a potentially costly endeavour both in terms of increased mortality risk (Rushing et al, 2016(Rushing et al, , 2017Sillett & Holmes, 2002; but see Zúñiga et al, 2017) and metabolic expenditures (Alves et al, 2013;Brown et al, 2023;Wikelski, Tarlow, et al, 2003), suggesting that migration might be associated with a fast POL.…”

Seasonal migration alters energetic trade-off optimization and shapes life history

“…Recent work has suggested a high-latitude origin for most avian migrations as opposed to earlier theories which posit a “southern home” (Bruderer & Salewski 2008; Winger et al . 2011, 2019; Yanco et al 2021). Our results provide theoretical justification for these observations in showing large realized fitness benefits of migration as compared to otherwise optimized non-migratory strategies.…”

“…Seasonal migration is a behavior with putatively substantial effects on realized POL but empirical findings about the direction and magnitude of those effects conflict (Soriano-Redondo et al 2020;Winger & Pegan 2021). Migration radically alters the environmental conditions an organism experiences, typically leading to relatively invariant conditions across the annual cycle (Nakazawa et al 2004;Gómez et al 2016;Merkle et al 2016;Thorup et al 2017;Zurell et al 2018;Alerstam et al 2019;Abrahms et al 2021;Yanco et al 2021) which might be expected to favor a slow POL. On the other hand, migration is a potentially costly endeavor both in terms of increased mortality risk (Sillett & Holmes 2002;Rushing et al 2016Rushing et al , 2017; but see Zúñiga et al 2017) and metabolic expenditures (Wikelski et al 2003b;Alves et al 2013;Brown et al 2023), suggesting that migration might be associated with a fast POL.…”

The association between haemosporidian infection and non-breeding moult location in great reed warblers revisited by combining feather stable isotope profiles and geolocator data

“…We also acknowledge that the positioning precision of light geolocation is limited (Lisovski et al 2012 ) and we may therefore be unable to geographically match possible vector habitats, such as patchy wetlands within an otherwise dry area. The currently available remedy for this limitation would be to use miniature archival GPS devices that allow much higher spatial resolution (Hallworth and Marra 2015 ; Yanco et al 2022 ). Finally, feather stable isotope signatures may reflect the local habitat more or less accurately depending upon the mobility of flying insects between isotopically different habitats (Quinby et al 2020 ).…”