Unexpectedly deep diving in an albatross

Albatrosses are the iconic aerial wanderers of the oceans, supremely adapted for long-distance dynamic soaring flight. Perhaps because of this they are considered poorly adapted for diving1, in contrast to many smaller shearwater and petrel relatives, despite having amphibious eyes2, and an a priori mass advantage for oxygen-storage tolerance3. Modern biologging studies have largely confirmed this view4,5, casting doubt on earlier observations using capillary tube maximum depth gauges1, which may exaggerate depths, and emphasising albatrosses’ reliance on near-surface feeding. Nevertheless, uncertainty about albatross diving remains an important knowledge gap since bycatch in human fisheries (e.g. birds becoming hooked when diving for longline bait fish) is thought to be driving many population declines in this most threatened group of birds6. Here we show, using miniature electronic depth loggers (TDRs), that black-browed albatross, Thalassarche melanophris, can dive to much greater depths (19 m) and for much longer (52 s) than previously thought — three times the maxima previously recorded for this species (6 m and 15 s), and more than twice the maxima reliably recorded previously for any albatross (from 113.7 bird-days of tracking4,5,7). Further evidence that diving may be a significant behavioural adaptation in some albatrosses comes from co-deployed 3-axis accelerometers showing that these deeper dives, which occur in most individuals we tracked, involve active under-water propulsion without detectable initial assistance from momentum, sometimes with bottom phases typical of active prey pursuit. Furthermore, we find (from co-deployed GPS) that diving occurs primarily in the distal portions of long-distance foraging trips, with deeper dives occurring exclusively during daylight or civil twilight, confirming the importance of visual guidance

Unexpectedly deep diving in an albatross

Albatrosses are the iconic aerial wanderers of the oceans, supremely adapted for long-distance dynamic soaring flight. Perhaps because of this they are considered poorly adapted for diving1, in contrast to many smaller shearwater and petrel relatives, despite having amphibious eyes2, and an a priori mass advantage for oxygen-storage tolerance3. Modern biologging studies have largely confirmed this view4,5, casting doubt on earlier observations using capillary tube maximum depth gauges1, which may exaggerate depths, and emphasising albatrosses’ reliance on near-surface feeding. Nevertheless, uncertainty about albatross diving remains an important knowledge gap since bycatch in human fisheries (e.g. birds becoming hooked when diving for longline bait fish) is thought to be driving many population declines in this most threatened group of birds6. Here we show, using miniature electronic depth loggers (TDRs), that black-browed albatross, Thalassarche melanophris, can dive to much greater depths (19 m) and for much longer (52 s) than previously thought — three times the maxima previously recorded for this species (6 m and 15 s), and more than twice the maxima reliably recorded previously for any albatross (from 113.7 bird-days of tracking4,5,7). Further evidence that diving may be a significant behavioural adaptation in some albatrosses comes from co-deployed 3-axis accelerometers showing that these deeper dives, which occur in most individuals we tracked, involve active under-water propulsion without detectable initial assistance from momentum, sometimes with bottom phases typical of active prey pursuit. Furthermore, we find (from co-deployed GPS) that diving occurs primarily in the distal portions of long-distance foraging trips, with deeper dives occurring exclusively during daylight or civil twilight, confirming the importance of visual guidance.Fundação para a Ciênica e Tecnologia - FCTinfo:eu-repo/semantics/publishedVersio

Manx shearwater (Puffinus puffinus) rafting behaviour revealed by GPS tracking and behavioural observations

Before visiting or leaving their remote island colonies, seabirds often engage in a behaviour termed ‘rafting’, where birds sit, often in groups, on the water close to the colony. Despite rafting being a widespread behaviour across many seabird taxa, the functional significance of rafting remains unknown. Here we combine global positioning system (GPS) tracks, observational and wind condition data to investigate correlates of rafting behaviour in Manx shearwaters (Puffinus puffinus) at a large colony on Skomer Island, Wales. We test (1) the influence of wind direction on rafting location and (2) whether raft size changes with respect to wind speed. Our approach further allows us to describe day-night trends in (3) raft distance from shore through time; (4) the number of birds present in the nearshore waters through time; and (5) spatial patterns of Manx shearwater rafts in marine waters adjacent to the breeding colony. We find no evidence that wind direction, for our study period, influences Manx shearwater rafting location, yet raft size marginally increases on windier days. We further find rafting birds closer to the shore at night than during the day. Thus, before sunset, birds form a “halo” around Skomer Island, but this halo disappears during the night as more individuals return from foraging trips and raft nearer the colony on Skomer Island. The halo pattern reforms before sunrise as rafts move away from land and birds leave for foraging. Our results suggest that wind conditions may not be as ecologically significant for rafting locations as previously suspected, but rafting behaviour may be especially important for avoiding predators and cleaning feathers

Shearwaters sometimes take long homing detours when denied natural outward journey information

The cognitive processes (learning and processing of information) underpinning the long-distance navigation of birds are poorly understood. Here, we used the homing motivation of the Manx shearwater to investigate navigational decision making in a wild bird by displacing them 294 km to the far side of a large island (the island of Ireland). Since shearwaters are reluctant to fly over land, the island blocked the direct route home, forcing a navigational decision. Further still, on the far side of the obstacle, we chose a release site where the use of local knowledge could facilitate a 20% improvement in route efficiency if shearwaters were able to anticipate and avoid a large inlet giving the appearance of open water in the home direction. We found that no shearwater took the most efficient initial route home, but instead oriented in the home direction (even once the obstacle became visible). Upon reaching the obstacle, four shearwaters subsequently circumnavigated the land mass via the long route, travelling a further 900 km as a result. Hence, despite readily orienting homewards immediately after displacement, shearwaters seem unaware of the scale of the obstacle formed by a large land mass despite this being a prominent feature of their regular foraging environment

Consistent concentrations of critically endangered Balearic shearwaters in UK waters revealed by at-sea surveys

Aim: Europe’s only globally critically endangered seabird, the Balearic shearwater (Puffinus mauretanicus), is thought to have expanded its post-breeding range northwards into UK waters, though its distribution there is not yet well understood. This study aims to identify environmental factors associated with the species’ presence, and map the probability of presence of the species across the western English Channel and southern Celtic Sea, and estimate the number of individuals in this area. Location: The western English Channel and southern Celtic Sea. Methods: This study analyses strip transect data collected from vessel-based surveys in the western English Channel and southern Celtic Sea during the shearwater’s post-breeding period between 2013 and 2017. Using environmental data collected directly and from remote sensors both Generalized Additive Models (GAMs) and the Random Forest (RF) machine learning model were used to determine shearwater presence at different locations. Results: Both models indicated that oceanographic features were better predictors of shearwater presence than fish abundance. Seafloor aspect, sea surface temperature, depth, salinity, and maximum current speed were the most important predictors. Based on the timing of the surveys (mainly in October) it is probable that most of the sighted shearwaters were immatures. Main conclusions: Areas with consistently high probabilities of shearwater presence were identified at the Celtic Sea front. Our estimates suggest that the study area in southwest Britain supports between 2% and 23% of the global population of Balearic shearwaters. This study provides the most complete understanding of Balearic shearwater distribution in UK waters available to date, information that will help inform any future UK conservation actions concerning this endangered 38 species

Optimization of dynamic soaring in a flap-gliding seabird affects its large-scale distribution at sea

Dynamic soaring harvests energy from a spatiotemporal wind gradient, allowing albatrosses to glide over vast distances. However, its use is challenging to demonstrate empirically and has yet to be confirmed in other seabirds. Here, we investigate how flap-gliding Manx shearwaters optimize their flight for dynamic soaring. We do so by deriving a new metric, the horizontal wind effectiveness, that quantifies how effectively flight harvests energy from a shear layer. We evaluate this metric empirically for fine-scale trajectories reconstructed from bird-borne video data using a simplified flight dynamics model. We find that the birds’ undulations are phased with their horizontal turning to optimize energy harvesting. We also assess the opportunity for energy harvesting in long-range, GPS-logged foraging trajectories and find that Manx shearwaters optimize their flight to increase the opportunity for dynamic soaring during favorable wind conditions. Our results show how small-scale dynamic soaring affects large-scale Manx shearwater distribution at sea.publishedVersio

Optimization of dynamic soaring in a flap-gliding seabird affects its large-scale distribution at sea

Funding: This work was supported by the University of Oxford Christopher Welch Scholarship (to J.A.K.); ASAB Undergraduate Project Scholarship (to J.A.K.); UKRI BBSRC scholarship grant number BB/M011224/1 (to J.W. and N.G.); The Queen’s College, University of Oxford (to A.L.F.); Junior Research Fellowship at St. John’s College, University of Oxford (to O.P.); Merton College, University of Oxford (to T.G.); Mary Griffiths Award (to T.G.); BBSRC David Phillips Fellowship grant numbers BB/G023913/1 and BB/ G023913/2 (to C.R.); and Jesus College, University of Oxford (to G.K.T.). This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 682501) (to G.K.T.)Dynamic soaring harvests energy from a spatiotemporal wind gradient, allowing albatrosses to glide over vast distances. However, its use is challenging to demonstrate empirically and has yet to be confirmed in other seabirds. Here, we investigate how flap-gliding Manx shearwaters optimize their flight for dynamic soaring. We do so by deriving a new metric, the horizontal wind effectiveness, that quantifies how effectively flight harvests energy from a shear layer. We evaluate this metric empirically for fine-scale trajectories reconstructed from bird-borne video data using a simplified flight dynamics model. We find that the birds' undulations are phased with their horizontal turning to optimize energy harvesting. We also assess the opportunity for energy harvesting in long-range, GPS-logged foraging trajectories and find that Manx shearwaters optimize their flight to increase the opportunity for dynamic soaring during favorable wind conditions. Our results show how small-scale dynamic soaring affects large-scale Manx shearwater distribution at sea.Publisher PDFPeer reviewe

Avoidance of different durations, colours and intensities of artificial light by adult seabirds

There is increasing evidence for impacts of light pollution on the physiology and behaviour of wild animals. Nocturnally active Procellariiform seabirds are often found grounded in areas polluted by light and struggle to take to the air again without human intervention. Hence, understanding their responses to diferent wavelengths and intensities of light is urgently needed to inform mitigation measures. Here, we demonstrate how diferent light characteristics can afect the nocturnal fight of Manx shearwaters Pufnus pufnus by experimentally introducing lights at a colony subject to low levels of light pollution due to passing ships and coastal developments. The density of birds in fight above the colony was measured using a thermal imaging camera. We compared number of fying shearwaters under dark conditions and in response to an artifcially introduced light, and observed fewer birds in fight during ‘light-on’ periods, suggesting that adult shearwaters were repelled by the light. This efect was stronger with higher light intensity, increasing duration of ‘light-on’ periods and with green and blue compared to red light. Thus, we recommend lower light intensity, red colour, and shorter duration of ‘light-on’ periods as mitigation measures to reduce the efects of light at breeding colonies and in their vicinity

Case Report of Puffinosis in a Manx Shearwater (Puffinus puffinus) Suggesting Environmental Aetiology

Publication history: Accepted - 1 December 2022; Published online - 7 December 2022Puffinosis is a disease of a range of seabirds characterised by dorsal and ventral blistering of their webbed feet, conjunctivitis, dry necrosis, leg spasticity, head shaking, loss of balance, tremors, and death. It is associated with Manx shearwaters (Puffinus puffinus), frequently affecting chicks within their underground nesting burrows. The aetiology of the disease is unclear but has been attributed to a type-2 coronavirus associated with Neotombicula mites as a potential vector. However, there is some uncertainty given potential laboratory contamination with mouse hepatitis virus and failure to fulfil Koch’s postulates, with birds injected with isolates remaining healthy. We describe a detailed case report of puffinosis in a Manx Shearwater covering necropsy, histology, bacteriology, and metagenomics including viral sequencing. We found no evidence of viral infection or parasites. Our results are consistent with an entirely environmental aetiology, with caustic faecal ammonia in damp nesting burrows causing conjunctivitis and foot dermatitis breaking the skin, allowing common soil bacteria (i.e., Flavobacterium, Staphylococcus and Serratia spp., Clostridia perfringens and Enterococcus faecalis) to cause opportunistic infection, debilitating the bird and leading to death. A similar condition (foot pad dermatitis or FPD) has been reported in broiler chickens, attributed to caustic faeces, high humidity, and poor environmental conditions during indoor rearing, preventable by adequate ventilation and husbandry. This is consistent with puffinosis being observed in Shearwater nesting burrows situated in tall, dense, vegetation (e.g., bracken Pteridium aquilinum) but rarely reported in burrows situated in well-ventilated, short coastal grasslands. This proposed environmental aetiology accounts for the disease’s non-epizootic prevalence, spatial variation within colonies, and higher frequency in chicks that are restricted to nesting burrows.Niamh Esmonde was supported by a UKRI QUADRAT Doctoral Training Programme (DTP) studentship, grant number NE/S007377/1 funded by the Natural Environment Research Council (NERC). The Agri-Food and Biosciences Institute (AFBI) funded the costs of necropsy, histology, bacteriology, parasitology, and metagenomics as part of the Queen’s–AFBI Alliance. Jignasha Patel, who conducted the metagenomics, was funded by the Research Leaders 2025 Programme cofounded by Teagasc and the European Union Horizon 2020 Research and Innovation Programme under a Marie Skłodowska-Curie grant (grant 754380). Paris Jaggers was supported by a UKRI NERC scholarship (grant NE/S007474/1)

Long-term spatiotemporal stability and dynamic changes in helminth infracommunities of spiny mice (Acomys dimidiatus) in St. Katherine’s Protectorate, Sinai, Egypt

The importance of parasites as a selective force in host evolution is a topic of current interest. However, short-term ecological studies of host-parasite systems, on which such studies are usually based, provide only snap-shots of what may be dynamic systems. We report here on four surveys, carried out over a period of 12 years, of helminths of spiny mice (Acomys dimidiatus), the numerically dominant rodents inhabiting the dry montane wadis in the Sinai Peninsula. With host age (age-dependent effects on prevalence and abundance were prominent) and sex (female bias in abundance in helminth diversity and in several taxa including Cestoda) taken into consideration, we focus on the relative importance of temporal and spatial effects on helminth infracommunities. We show that site of capture is the major determinant of prevalence and abundance of species (and higher taxa) contributing to helminth community structure, the only exceptions being Streptopharaus spp. and Dentostomella kuntzi. We provide evidence that most (notably the Spiruroidea, Protospirura muricola, Mastophorus muris and Gongylonema aegypti, but with exceptions among the Oxyuroidae e.g. Syphacia minuta), show elements of temporal-site stability, with rank order of measures among sites remaining similar over successive surveys and hence some elements of predictability in these systems