Diverse migration strategies in hoopoes (Upupa epops) lead to weak spatial but strong temporal connectivity

Abstract

The annual cycle of migrating birds is shaped by their seasonal movements between breeding and non-breeding sites. Studying how migratory populations are linked throughout the annual cycle-migratory connectivity, is crucial to understanding the population dynamics of migrating bird species. This requires the consideration not only of spatial scales as has been the main focus to date but also of temporal scales: only when both aspects are taken into account, the degree of migratory connectivity can be properly defined. We investigated the migration behaviour of hoopoes (Upupa epops) from four breeding populations across Europe and characterised migration routes to and from the breeding grounds, location of non-breeding sites and the timing of key migration events. Migration behaviour was found to vary both within and amongst populations, and even though the spatial migratory connectivity amongst the populations was weak, temporal connectivity was strong with differences in timing amongst populations, but consistent timing within populations. The combination of diverse migration routes within populations and co-occurrence on the non-breeding grounds between populations might promote exchange between breeding populations. As a result, it might make hoopoes and other migrating bird species with similar strategies more resilient to future habitat or climatic changes and stabilise population trends.

Experimental old nest material predicts hoopoe Upupa epops eggshell and uropygial gland microbiota

“…There can be partial migrant populations in areas with low seasonal differences, like in our study population, where sedentary and migratory specimens reproduce (Reichlin et al 2013, van Wijk et al 2018). This species is a migratory bird distributed throughout Europe, Africa and Asia.…”

“…This species is a migratory bird distributed throughout Europe, Africa and Asia. There can be partial migrant populations in areas with low seasonal differences, like in our study population, where sedentary and migratory specimens reproduce (Reichlin et al 2013, van Wijk et al 2018). Hoopoes do not carry nest materials, but if soft materials are present in the cavity selected, females excavate a slight depression where they lay the eggs (Martín-Vivaldi et al 2014b).…”

“…However, our experimental results do not agree with such prediction and hoopoes used at similar rates nest boxes with or without material taken from nests where hoopoes reproduced the previous season. However, we have very few recruits (11.36% in 2015; 4 of 44 females) due to high mortality and high dispersion of the species (van Wijk et al 2018). Previous studies have pointed out that hoopoes commonly re-use cavities for reproduction (Cramp 1998, Martín-Vivaldi et al 1999, van Wijk et al 2017.…”

“…We do not have a reliable criterion for estimating age in the females of this breeding season so we cannot control for it in the analyses. However, we have very few recruits (11.36% in 2015; 4 of 44 females) due to high mortality and high dispersion of the species (van Wijk et al 2018). Thus, most breeders were new individuals arrived from other places to our study area.…”

Remarkably similar migration patterns between different red‐backed shrike populations suggest that migration rather than breeding area phenology determines the annual cycle

“…Thus, to maximize overall fitness (Barta et al , Harrison et al ), being on time may be important, not only during the breeding season but throughout the annual cycle. The temporal constraints of migration may vary between populations (Flack et al , van Wijk et al ). However, the extent to which the annual cycle constrains migratory schedules across populations remains unexplored.…”