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Differences in on-ground and aloft conditions explain seasonally different migration paths in Demoiselle crane

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journal contribution
posted on 01.01.2022, 00:00 authored by Batbayar GaltbaltBatbayar Galtbalt, Nyambayar Batbayar, Tuvshintugs Sukhbaatar, Bernd Vorneweg, Georg Heine, Uschi Müller, Martin Wikelski, Marcel KlaassenMarcel Klaassen
Abstract
Background: Although some migratory birds may take different routes during their outbound and inbound migration, the factors causing these differential migrations to and from the breeding grounds, have rarely been investigated.In Northeast Asia, Demoiselle crane (Anthropoides virgo) performs one of the most extreme “loop” migrations known to date. During outbound migration, they cross the Himalayas to non-breeding sites in northwest India. Contrastingly, during inbound migration to the breeding grounds, they fly around the western end of the Himalayas. We hypothesise that differences in prevailing environmental conditions aloft and/or on-ground during both seasonal migrations are at the core of this phenomenon.
Methods: Based on the tracking data of 16 individuals of tagged Demoiselle crane, we compared conditions during
actual migration with those of simulated “reverse” migration (i.e. by adding 180 degrees to the flight direction and adding and subtracting half a year to the timestamps of outbound and inbound migration, respectively).
Results: The comparison of actual and simulated “reverse” migration indicated that cranes would have encountered
poorer aloft (wind support and thermal uplift) and on-ground conditions (temperature) if they had migrated in a
reverse outbound migration and poorer on-ground conditions (Normalised Difference Vegetation Indexes [NDVI]) if they had migrated in a reverse inbound direction.
Conclusions: Our analyses suggest that both on-ground and aloft conditions play a key role in explaining Demoiselle cranes’ loop migration, during the periods that they chose to use these alternative routes. Knowledge on the determinants of (differential) migration routes allow predicting migration decisions and may be critical in mitigating global change effects on animal migrations.

History

Journal

Movement Ecology

Volume

10

Article number

4

Pagination

1 - 11

Publisher

BioMed Central

Location

London, Eng.

eISSN

2051-3933

Language

eng

Publication classification

C1 Refereed article in a scholarly journal