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Effective conservation management of the Critically Endangered European eel (Anguilla anguilla) is hindered by incomplete understanding of distribution, abundance, and habitat requirements at the catchment scale.All habitats available to eels within a small, highly regulated river catchment, representative of many used across the species' range, were sampled using several methods (including point abundance sample electric fishing and fyke nets) and supplemented by individual telemetry to investigate movements.Eels were found throughout the catchment (59% of n = 131 sites) from the coastal marshes to the headwaters, although the probability of presence declined with distance from the estuary. The lack of a clear relationship with perceived barriers may illustrate a mismatch with the reality experienced by eels, as telemetry identified connectivity across obstacles between paludal habitat and estuary, and detected escapement of mature silver eels from both lotic and lacustrine habitat.Different size/age classes occurred in different parts of the catchment, partly linked to different habitat associations, with coastal paludal habitat supporting >50% of the catchment population and especially smaller (possibly male dominated) yellow eels. Recently recruited elvers were most abundant in the lower reaches of lotic habitat. The largest (probably female) eels were concentrated in lacustrine sites, especially at the 'end‐of‐the‐line' in the headwaters.Experiences here suggest that conservation management for eels in small catchments is best focused on: (i) improving connectivity and assisting migration of elvers across 'problem' barriers that cannot be removed or modified, (ii) river restoration and rewilding, especially measures that increase instream woody material to provide refuge habitat and, (iii) enhancement or creation (where necessary) of suitable lacustrine habitat to benefit large females in particular. Such action across numerous small river catchments may ultimately help support the recovery of eel stocks. [ABSTRACT FROM AUTHOR]

Tracking tags have been used to map the distributions of a wide variety of avian species, but few studies have examined whether the use of these devices has impacts on the study animals that may bias the spatial data obtained. As Global Positioning System (GPS) tags small enough for deployment on terns (family: Laridae) have only recently become available, until now tracking of this group has been conducted by following unmanipulated individuals by boat, which offers a means of comparing distributions obtained from GPS‐tracking. We compared the utilization distributions (UDs) of breeding Arctic Terns Sterna paradisaea obtained by GPS‐tracking 10 individuals over 2 weeks, with UDs derived from contemporaneous visual boat tracks from 81 individuals. The 50% and 95% UDs of both methods had high similarity scores, indicating good agreement in the density distributions derived from the two methods. The footprints of the UDs of tagged birds were ~ 75–80% larger, which may reflect an effect of tagging on foraging range or the occasional inability to follow by boat individuals which roamed further from the colony. We also compared the nest attendance and chick provisioning rates of adults that were (1) fitted with a GPS tag and leg‐flag, (2) handled and marked with a leg‐flag but not tagged and (3) fitted with a leg‐flag in a previous year but unhandled in the year of the study. There was some evidence that birds fitted with both a GPS tag and leg‐flag spent slightly less time at the nest compared with unhandled birds and those fitted with a leg‐flag only. Both treatments where birds were fitted with a leg‐flag in the year of the study had similarly lower provisioning rates to those of unhandled control birds > 48 h after handling, suggesting that negative effects on provisioning are due to capture and handling or leg‐flag attachment rather than to GPS tag attachment/loading per se. Overall brood‐provisioning rate was compensated for by the increased effort by the unhandled partner. Our study suggests that despite slight effects of GPS‐tagging on behaviour, the estimates of marine density distribution obtained were very similar to those of unmanipulated birds. [ABSTRACT FROM AUTHOR]

Rockabill, in Co. Dublin, supports the most important colony of Roseate Terns Sterna dougallii in Europe, testament to intense conservation effort over the last 30 years. This paper describes the first boat-based visual tracking of Roseate Terns from Rockabill and relates this to observations of chick provisioning at the colony. Roseate Terns are capable of rapid flight and routinely forage up to 30 km from the colony. Characteristic 'power diving' from a relatively low height allows birds to reach greater depths than similar-sized terns, offering a competitive advantage, especially in deep, clear, oceanic waters. Birds are drawn to foraging auks, which bring schooling 'bait fish' to the surface, but Roseates seem to be outcompeted by other seabirds, especially Common Terns S. hirundo, in the ensuing melee and may be more successful foraging alone. Adult Roseates from Rockabill fed mainly on small fish (<3 cm in length) but carried larger clupeids or sandeels to provision chicks. Further work is needed to test the idea that a local stock of Atlantic Herring Clupea harengus may be of fundamental importance to the success of the Rockabill colony. [ABSTRACT FROM AUTHOR]

The Sandwich Tern Sterna sandvicensis is a familiar seabird yet little is known about its foraging ecology. This paper brings together the results from four years of boat-based visual tracking of Sandwich Terns from the UK’s largest breeding colonies, at Blakeney Point and Scolt Head, within the North Norfolk Coast SPA. Sandwich Tern is something of a ‘super tern’, capable of ranging more than 50 km from the colony at an average speed of 32 km/h and a median height of 25-30 m in a search for patchily distributed prey, which is typically captured by plunge diving with full immersion. Birds generally foraged alone but concentrated at ‘hotspots’, including those created by predatory fish, auks or marine mammals pursuing schooling ‘bait fish’ to the surface. Adults generally consumed small prey (<3 cm in length) but selected and carried larger clupeids or sandeels (up to 25 cm) to provision chicks. Our work has contributed to conservation planning for Sandwich Terns. [ABSTRACT FROM AUTHOR]