The loss of biodiversity is one of the most pressing issues globally. Efforts to tackle the issue include the use of protected areas, which are designated to protect species and/or their habitats from anthropogenic threats. But how effective are protected areas at achieving the desired biodiversity benefits?

The European Union’s Natura 2000 network is the largest continent-wide effort to conserve biodiversity through a protected area network. The Natura 2000 sites are designated across the EU under either the Birds Directive or the Habitats Directive, based on objective assessment of a site’s importance for species (Special Protection Areas – SPAs) or habitats (Special Areas of Conservation Concern – SACs). Following the UK’s departure from the European Union, these sites are now covered under domestic legislation. They enable the UK to meet its international obligations for biodiversity conservation through protected area coverage. But how effective are these sites, and are they more effective than other forms of site protection? While there is plenty of evidence to demonstrate that protected areas are effective at protecting natural habitats, their benefits for birds and other species have been less well-studied. This study uses data from the BTO/JNCC/RSPB Breeding Bird Survey (BBS) to explore the effectiveness of the Natura 2000 protected areas for UK bird species of conservation concern (Red and Amber-Listed). In addition, the study also examines the effectiveness of Sites of Special Scientific Interest (SSSIs), which receive a lower degree of legislative protection than SPAs or SACs. The authors used BBS data from two periods, the first covering 1995–1999 (before the majority of Natura 2000 sites were designated), and the second from 2011–2015 (immediately prior to the UK’s departure from the European Union). This approach enabled the authors to test the influence of protected areas on bird populations, revealing that the abundance of birds of conservation concern was higher on BBS squares that were within Natura 2000 sites, and on squares with a greater proportion of Natura 2000 coverage within 5 km. Interestingly, the abundance of birds of conservation concern was not higher on BBS squares with a greater proportion of SSSI-only coverage, though it was positively related to proportion of SSSI coverage in the surrounding 5 km. These results demonstrate that the abundance of birds of conservation concern increases with protected area coverage, both within the survey square itself and in the surrounding area. This suggests that there is a ‘spillover effect’, in which protected sites may benefit birds in the surrounding area. The effect was greater for SPAs and SACs than for SSSIs. The study highlights both the value and benefits of this high level of legislative protection upon which the UK continues to rely to meet a number of its international commitments for nature. Protected sites will always be a key tool for securing the future of birds and wider biodiversity in the UK, so it is vital that we understand where and how this protection works best. This study also demonstrates the critical role BBS data play in enabling such assessments to be carried out.

BTO research underlines the importance of assessing the impact of tagging on a species by species basis, and suggests that the tag-attachment methods successfully used on other seabird species might not be suitable for Red-listed Kittiwakes. Biologging devices including GPS and satellite tags, which attach to individual animals and collect information on their movements, are increasingly deployed in ecology and conservation research. They can be particularly useful for species like seabirds, which are otherwise hard to monitor as they spend so much of their lives in inaccessible environments. Many seabird species spend most of their lives far out in the open ocean, where visual surveillance, particularly of focal individuals, is almost impossible. Even when they come to land, during the breeding season, their breeding sites may be on dangerous cliff ledges or deep, fragile burrows. At the same time, large numbers of seabird species are in decline, so it is essential to better understand their life cycles to identify pinch points and effectively target conservation action. BTO scientists have been attaching GPS devices to seabirds for more than a decade. While this has proved successful for some species, including Herring Gulls and Lesser Black-backed Gulls, it has been problematic for others. For example, Great Skuas failed to return to their nest sites the year after they were GPS-tagged, leading BTO to cancel this particular strand of research. In this study, BTO scientists collaborated with others to assess the impact of attaching tagging devices to Kittiwakes breeding in the UK and Norway. The Kittiwake is on the UK Birds of Conservation Concern Red List, having undergone a sharp reduction in numbers in recent decades. It is a small, surface feeding gull that has a more maritime lifestyle than other gull species successfully tagged by BTO. The researchers trialled different harness types for attaching tags – one that looped around the birds’ legs, and another that fitted around the birds’ wings and thorax – and then recaptured the birds 10-24 days later to examine whether there had been any adverse effects. They also monitored the birds at their breeding colony, and compared their behaviour to that of control birds, which were captured and ringed, but were not fitted with a tracking device. The study showed damage to the tagged Kittiwakes’ feathers and skin around the area under the tag and the tag’s harness. This damage, which included feather wear and skin lesions, was worse for the thoracic harness than for the leg-loop version – the birds fitted with leg-loop harnesses showed abrasion to the feathers but not the skin. Kittiwakes are known to lose weight during the breeding season, but this effect was marginally worse in tagged birds than in the control cohort. As a result of this study, the authors recommend that thoracic harnesses should not be used on Kittiwakes. Leg-loop harnesses could still be a viable option, especially if different harness materials are trialled, for example those that are more elastic than the Teflon cord used in this study. This work underlines the importance of continually assessing the suitability of tracking technology for different species, and reporting unsuccessful results to both ensure negative impacts are not repeated between multiple studies but also to improve overall practice. Small differences in the materials, design or procedure can be very important in tracking studies and through continual appraisal, some species can now be safely tracked which could not have been previously.

Widespread declines in breeding performance have caused the IUCN to classify the Curlew as near-threatened. The UK hosts an internationally significant overwintering population, but conservationists fear that impending habitat loss due to sea-level rise will put even greater pressure on this struggling species. Building new intertidal habitat to compensate for these losses is one viable counteraction, but in order to make effective management decisions, we must first understand how Curlew use their winter home range. In a collaborative study led by the University of Hull, BTO scientists aimed to find out more by establishing the overwinter home range size (the size of the space used by the birds during winter) of Curlew in the Humber Estuary, North-East England, UK. Curlew visit both estuarine and agricultural habitats during winter, but this study may be the first to examine how this habitat use changes throughout the non-breeding season. As Curlew display sex-differences in bill length which impact foraging technique, this study also wanted to determine if males and females used habitats differently. Over the course of four winters, GPS tags were deployed on 18 Curlew from two sites (Welwick Marsh and Long Bank Marsh) on the Humber Estuary. An in-depth analysis of these GPS data allowed the researchers to estimate the home range size of the individual birds and, for the first time in a wader species, infer their behaviour from their movement patterns. These analyses revealed where and how the Curlew were spending their time, both on a daily basis and across the season. The study uncovered a number of surprising results. The Curlews’ average home range size was 76.1 ha, which is considered small when compared to other wading species such as Knot and Dunlin. Furthermore, contrary to expectations, a slight decrease in Curlews’ home range size was detected as the winters progressed. These results imply that the high-quality habitats of the Humber Estuary had a plentiful supply of food, meaning the birds were not forced to travel long distances or expand their home ranges in response to resource depletion. Unexpectedly, although the Curlew spent more time resting at night (31% compared to 13% during the day), their nocturnal home range was often larger than their diurnal one. Home range characteristics and use also differed between individuals. For example, some birds travelled up to 3.5 km inland to forage on farmland, while others stayed exclusively on tidal mudflats. Contrary to predictions, these differences were not explained by sex. Instead, Curlew foraging behaviours varied between groups of birds wintering at different locations on the estuary. The drivers behind these individual differences remain cryptic, but it is probable that Curlew employ specialised foraging tactics to avoid competing with one another. As conservationists aim to support their survival, they should account for this variety of strategies when maintaining habitat on the Curlews’ behalf. Although these findings may be site specific, the valuable knowledge that Humber Estuary Curlew maintain relatively small home ranges and employ individualised foraging strategies will inform management responses to sea-level rise and habitat conservation. Crucially, this study also demonstrates there is still much to learn about Curlew habitat use, paving the way for future work.

Urban areas can and do hold significant populations of birds, but we know surprisingly little about how these populations are connected with those present within the wider countryside. It has been suggested that the populations using these different habitats may be linked through seasonal movements, with individuals breeding in rural areas moving into urban sites during the winter months to exploit the supplementary food provided at garden feeding stations. However, little work has been done to test this hypothesis.