Factors influencing nest site selection in a rapidly declining shorebird, the Eurasian curlew
Author(s): Rivers, E.M., Short, M.J., Page, A., Potts, P.M., Hodder, K., Hoodless, A., Robinson, R. & Stillman, R.
Published: December 2024
Journal: Journal of Avian Biology
Article No.: e03286
Digital Identifier No. (DOI): 10.1111/jav.03286
This paper reports on work done studying Curlew in the New Forest, in collaboration with the University of Bournemouth, and in association with the Game and Wildlife Conservation Trust. In the New Forest Curlew nest in three habitats, and the outcome of 76 nests across these was recorded: dry heath (31 nests), wet heath (20) and wet mire (25).
Dry heath is by far the most extensive habitat, but is used proportionally much less than the wetter habitats. Conversely, more nests were found in the wet mire habitat than might be expected if nests were placed at random. So why this preference? In wet mire habitats around 21% of all nesting attempts survived to long enough to hatching (chicks leave the nest soon after). In wet heath, around 13% of nests survive, whilst in dry heath only 5% survived. Similarly, areas close to scrub and woodland experienced higher levels of nest failure.
Despite dry heath being much the most extensive habitat then, it was also the most perilous place for a Curlew to try and nest. Typically, dry heaths in the New Forest support dense networks of narrow pathways created by deer and livestock, and trails like these are often used by Foxes and Badgers which are major predators of Curlew (and other ground-nesting bird) nests. They are also likely to experience higher levels of human disturbance, potentially increasing predation risk and nest exposure time. This work highlights the importance of ensuring there is enough protected habitat that birds can nest safely to raise enough chicks to support a healthy population.
Abstract
with large-bodied birds at the greatest risk of extinction. Productivity and adult survival cannot both be maximised concurrently, and individuals will make decisions during the nest-placement phase which will favour one outcome or the other; however, under conditions of accelerating change, these decision processes may become decoupled from positive fitness outcomes. The Eurasian curlew Numenius arquata is Europe’s largest wader and is showing steep declines in breeding productivity. Curlews are known to use a diverse range of habitats for nesting, where anthropogenic or natural features may influence distribution. There is an urgent need to understand the spatial scales of these impacts, and whether habitat characteristics have a positive or negative impact on nest survival. In our study site in southern England, curlew showed a marked preference for nesting in wetter habitats, primarily mire, and a weaker selection of dry heathland. Nest survival improved in wetter habitats, and the area of mire round a nest site was positively associated with increased levels of nesting success, whilst area of scrub had a negative association. Woodland significantly excluded curlew from potentially suitable breeding habitat, with an impact observed up to 2 km from the nest site, but nest survival did not improve with distance from woodland. Curlews strongly avoided nesting near a major road passing through the study site, despite seemingly suitable habitat nearby. Understanding landscape effects will assist in planning future habitat management for curlew, impacts of forestry and avoidance of additional pressures on a species of high conservation concern.
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