High winter site fidelity in a long-distance migrant: implications for wintering ecology and survival estimates

Abstract

12The decision for a migratory animal to be site faithful in its non--breeding season has 13 profound implications for migratory connectivity, resilience to winter habitat loss 14 and population dynamics through carry--over effects on future breeding success and 15 fitness. Knowledge of the temporal and spatial scale of site fidelity and dispersal is 16 also central to accurate survival estimates. We established the observed spatial and 17 temporal scale of site fidelity and the ability to detect small--scale dispersal within 18 and between years for a wintering long--distance Palearctic migrant, the Whinchat 19 Saxicola rubetra, by comparing predicted and observed detection rates within the 20 study site. Across two years, 54% of birds returned to the study site and all returning 21 birds reoccupied the territories they used in the previous winter. Observed dispersal 22 was very low despite the high probability of detecting any local dispersal, suggesting 23 that return rates are indicative of true between--winter survival rates for this 24 population. In any winter, 50% of returning individuals had a previously occupied but 25 now empty territory that was less than one territory--span away from the centre of 26 their current territory; high site fidelity was therefore very unlikely to be because of 27 limited territory availability. Over--winter residency time (defined by departure 28 month) differed significantly across sites and with age, but did not determine the 29 probability of whether a bird returned in the following year. This suggests the use of 30 more than one wintering site for some individuals, rather than reduced over--winter 31 survival. This study is one of the first to comprehensively document site fidelity at 32 the territory scale in a Palearctic system, although less comprehensive studies or 33 anecdotal evidence suggest that high winter site fidelity may be relatively common. 34Here we provide evidence for the serial residency hypothesis, where selection acts 35 for individual migrants to have generalist habitat requirements, allowing them to 36 survive in and remain site faithful to even relatively low quality, but sufficient and 37 familiar sites. Lower dispersal and higher site fidelity compared to that during 38 breeding suggest that annual survival estimates are more accurate when measured 39 on the wintering grounds. This study supports previous findings that wintering 40 conditions do not limit Whinchat populations.

Philopatry and Regional Connectivity of the Great Hammerhead Shark, Sphyrna mokarran in the U.S. and Bahamas

“…Such annual reuse of particular areas has long been documented across the animal kingdom, including sea turtles (Schofield et al, 2010), bats (Hillen et al, 2009) and birds (Blackburn and Cresswell, 2016), and is emerging as a widespread behavior for large-bodied coastal and oceanic sharks (Chapman et al, 2015). For example, tiger (Galeocerdo cuvier), lemon and oceanic whitetip sharks tracked in the same region exhibited, repeated migratory philopatry to overwintering sites (HoweyJordan et al, 2013;Kessel et al, 2014a;Lea et al, 2015).…”

An experimental evaluation of the effects of geolocator design and attachment method on between‐year survival on whinchats Saxicola rubetra

“…Control birds were captured, handled and colour‐ringed as per tagged birds, except that no tag was fitted. Control birds were mainly ringed as part of a larger study into whinchat wintering ecology from January 2012 until March 2014 (Blackburn and Cresswell , ). We resighted both tagged and control whinchats to establish a) the degree of residency in their winter of capture, and b) whether a bird had returned the following winter.…”

“…We resighted both tagged and control whinchats to establish a) the degree of residency in their winter of capture, and b) whether a bird had returned the following winter. Some whinchats in the study area had relatively short residency periods, with evidence of an increase in transient or passage individuals towards the end of the wintering period (Blackburn and Cresswell ) so that a colour‐ringed whinchat might be present for one half of the wintering period. For whinchats ringed in year 1, resighting for birds returning in the following winter was carried out systematically from October to January.…”

Wintering space use and site fidelity in a nomadic species, the snowy owl

“…Defined as the way individuals use environmental components to meet their life history needs (Block andBrennan 1993, Jones 2001), habitat use can be influenced by multiple factors during winter such as food abundance or its accessibility, which can be limited by environmental factors such as snow cover in winter (Greenwood andBaillie 1991, Golawski andKasprzykowski 2010). Despite such environmental variability, some migrating species will show relatively high fidelity to a specific wintering site because familiarity with a given site may improve foraging efficiency, predator avoidance or maintain a dominant status, which could ultimately increase individual fitness (Cresswell 2014, Blackburn and Cresswell 2016, Latta et al 2016. Site fidelity is generally favoured when resource levels are predictable in space and time (Newton 2006(Newton , 2008.…”