TY - THES

T1 - Population decline of waders and vigilance behaviour in the Eurasian Curlew

AU - King, Alex

PY - 2025

Y1 - 2025

N2 - Global biodiversity loss is continuing, and birds such as the waders Eurasian Curlew, Northern Lapwing, Oystercatcher, Redshank, and Common Snipe, are no exception. These birds occupy a wide variety of habitats during the breeding and non-breeding winter season and are in turn exposed to a variety of threats, most of which stem from human activity. By developing our understanding of the threats to waders, we can work to mitigate their effects and improve survival rates of waders. One habitat that is under threat is high tide roost sites, which are vital for wintering waders as they offer protection from predators and allow birds to rest and conserve energy when their low tide feeding areas are not available. However, wader roost behaviour and their response to threats is still poorly understood, particularly in endangered species such as Eurasian Curlew. Vigilance behaviours can be used as a visible measure of the effect of disturbance and can give insight into the perceived threat levels from disturbance sources. In Chapter 1, the current understanding of the drivers of population decline of waders is reviewed, including the role of habitat loss and land use change, the reduction in reproductive success, the non-breeding winter season, and the impact of recreational disturbance. Low productivity rates are the dominant reason for wader decline, driven by a combination of factors that lead to an overall negative impact on nesting habitat, food availability, predation rates, nest destruction, and vegetation change. Similarly, waders at coastal wintering sites face increased survival pressures from low temperatures and extreme weather, the effects of which are compounded by the additional energy expenditure from recreational disturbance, and the loss of food sources and roost sites from land use change. We identify gaps in knowledge surrounding the reduction of predation in the breeding season and the mechanisms behind the effects of low temperatures on waders in the winter period, as well as issues with current efforts to slow population declines. In Chapter 2, vigilance behaviour of Eurasian Curlews is investigated, to test whether environmental and anthropogenic disturbances influence behaviour and long-term population trends. We measured the individual and group level behaviour of Eurasian Curlews at winter roost sites on the Isle of Man, and analysed these behaviours against environmental temperature, wind speed, group size, and the frequency of anthropogenic disturbance. We also analysed the effect of environmental temperature on long-term winter populations of Eurasian Curlew on the Isle of Man. Vigilance behaviour increased with group size and wind speed, but declined in low temperatures, however anthropogenic disturbance did not correspond to changes in vigilance behaviour, and we did not find correlation between temporal variation and environmental temperatures.

AB - Global biodiversity loss is continuing, and birds such as the waders Eurasian Curlew, Northern Lapwing, Oystercatcher, Redshank, and Common Snipe, are no exception. These birds occupy a wide variety of habitats during the breeding and non-breeding winter season and are in turn exposed to a variety of threats, most of which stem from human activity. By developing our understanding of the threats to waders, we can work to mitigate their effects and improve survival rates of waders. One habitat that is under threat is high tide roost sites, which are vital for wintering waders as they offer protection from predators and allow birds to rest and conserve energy when their low tide feeding areas are not available. However, wader roost behaviour and their response to threats is still poorly understood, particularly in endangered species such as Eurasian Curlew. Vigilance behaviours can be used as a visible measure of the effect of disturbance and can give insight into the perceived threat levels from disturbance sources. In Chapter 1, the current understanding of the drivers of population decline of waders is reviewed, including the role of habitat loss and land use change, the reduction in reproductive success, the non-breeding winter season, and the impact of recreational disturbance. Low productivity rates are the dominant reason for wader decline, driven by a combination of factors that lead to an overall negative impact on nesting habitat, food availability, predation rates, nest destruction, and vegetation change. Similarly, waders at coastal wintering sites face increased survival pressures from low temperatures and extreme weather, the effects of which are compounded by the additional energy expenditure from recreational disturbance, and the loss of food sources and roost sites from land use change. We identify gaps in knowledge surrounding the reduction of predation in the breeding season and the mechanisms behind the effects of low temperatures on waders in the winter period, as well as issues with current efforts to slow population declines. In Chapter 2, vigilance behaviour of Eurasian Curlews is investigated, to test whether environmental and anthropogenic disturbances influence behaviour and long-term population trends. We measured the individual and group level behaviour of Eurasian Curlews at winter roost sites on the Isle of Man, and analysed these behaviours against environmental temperature, wind speed, group size, and the frequency of anthropogenic disturbance. We also analysed the effect of environmental temperature on long-term winter populations of Eurasian Curlew on the Isle of Man. Vigilance behaviour increased with group size and wind speed, but declined in low temperatures, however anthropogenic disturbance did not correspond to changes in vigilance behaviour, and we did not find correlation between temporal variation and environmental temperatures.

U2 - 10.17635/lancaster/thesis/2896

DO - 10.17635/lancaster/thesis/2896

M3 - Master's Thesis

PB - Lancaster University

ER -