Grey seals (Halichoerus grypus) are a qualifying feature of three special areas of conservation (SACs) in Wales, yet relatively little is known of their site use along this coastline. Since 1992, many individuals and organisations have contributed to a grey seal photographic identification database held by Natural Resources Wales, which is one of the largest and oldest of its kind, providing key information from grey seal haul-out sites around the Celtic and Irish Seas. Here, we investigated spatial connectivity of haul-out sites and fidelity of adult females to breeding sites. The minimum number of adult female grey seals using the area between 1992 and 2016 was 2688. Individual capture histories and relative spatial transition probabilities (P ij) between pairs of location groups were calculated. Adjacent locations were highly connected (e.g. Lleyn Peninsula and Bardsey, P ij = 0.7) but connections spanned the entire region, up to 230 km apart (e.g. Skomer and Dee Estuary, P ij = 0.004). Resights were recorded within SACs (e.g. Lleyn Peninsula and Bardsey [Lleyn Peninsula and the Sarnau SAC], P ij = 0.7), between SACs (e.g. Bardsey and Skomer [Pembrokeshire Marine], P ij = 0.03), between SACs and non-designated areas (e.g. Skerries and Bardsey, P ij = 0.09) and between sites outside any protected area (e.g. Dee Estuary and Anglesey, P ij = 0.5). While inter-annual fidelity to breeding sites was high (P ij = 0.82-1), individual female grey seals moved throughout the region. This evidence of extensive site use beyond protected areas is important for the management and conservation of grey seals around Wales.
1. We need reliable information about the spatial and temporal distribution of mobile species to effectively manage anthropogenic impacts to which they are exposed.Yet, we often cannot sustain dedicated annual surveys and data obtained from platforms of opportunity offer an alternative avenue to understand where these species spend time.2. Four odontocete species that occur in the four-island region of Maui, Hawai'i, USA, are vulnerable to a range of human activities, but there is a lack of information regarding their distribution. We therefore do not know the extent of the risk these activities present for the conservation of these species (bottlenose dolphins, spinner dolphins, Pantropical spotted dolphins and false killer whales).3. We used a cross-validated maximum entropy (MaxEnt) occupancy model to estimate the distribution of these four species in an area extensively observed from platforms of opportunity (PoP). We then determined in a similar fashion whether the calves of those species were more likely to be observed in particular areas and whether distribution changed with season.4. Maxent models relying on local environmental variables described dolphin observations well (AUC > 0.7). Their distribution differed for all species when calves were present, indicating that different environmental variables describe area use for schools with calves present.5. The number of sighting events of all species varied significantly with season. Bottlenose dolphins and false killer whales were more prevalent in winter, while spotted and spinner dolphins were more prevalent in summer.6. We show that an overlap in the distribution of dolphin schools with calves and vessel traffic in the region could result in collision and chronic stress risks. This suggests a need for specific regulations for mitigating anthropogenic influences, such as acoustic disturbance or chronic energetic disturbance from vessel traffic.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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