1/13/2024 0 Comments Yellow rumped warbler juvenile![]() We found (i) sun-compass courses partially self-correct, making them most robust between flight-steps, (ii) within nocturnal flight-steps, geomagnetic or star-compass headings outperform cue-transferred sun-compass steps, (iii) across diverse airborne migration routes, the relative favourability of sun-compass over other courses increases with increasing goal-area, required flight steps and a spherical-geometry factor. We assessed robustness to errors among airborne compass courses and quantified inaugural migration performance globally, accounting for cue transfers (e.g., sun to star compass), in-flight cue maintenance, and previously-overlooked spherical-geometry (longitude) effects. Which if any such “compass courses” can explain narrow-front trans-continental routes remains unresolved, and evident error-corrections by naïve migrants remain unexplained. Migratory orientation of many animals is inheritable, enabling naïve migrants to reach remote destinations independently following stepwise (often, nightly) geomagnetic or celestial cues. Northwest origins likely respond to easterly displacement by orienting westerly to reestablish their previous migratory route. The result is most consistent with scenario three: individuals from (i.e., the more likely it was to have been displaced). Orientation directions became increasingly more west-northwesterly the further away an individual originated from the site Individuals that originated closer to the site tended to orient more southwesterly. Geographic origin, on orientation behavior. Because numerous factors influence migratory orientation (e.g.,įuel reserves, celestial cues), we simultaneously assessed the influence of body condition and cloud cover, in addition to We used video-based orientation registrationĬages to determine an individuals’ migratory orientation. Stable isotopes, we determined that stop-over migrants originated from nearby areas (and assumed on-course) and as far awayĪs western Hudson Bay, over 1,600km northwest (and assumed off-course) of the site. ![]() We hypothesized three scenarios after displacement: 1) continued orientation in the migratory direction selected before displacement,Ģ) orientation from the new location toward the previous destination, or 3) correction to regain the original pathway. Of juvenile yellow-rumped warblers (Dendroica coronata) captured at a stop-over site in southern Nova Scotia was related to where they originated from (i.e., likely on/off-course). Therefore, migrantsĪt stop-over sites along this route may be a mixture of on- and off-course individuals. Eastern North AmericaĮxperiences prevailing northwesterly winds during autumn, which could compel some migrants to drift eastward. Birds migrating along coastlines may be at increased risk if displacement occurs toward open-ocean.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |