Remotely sensing motion: the use of multiple biologging technologies to detect fine-scale, at-sea behaviour of breeding seabirds in a variable Southern Ocean environment

The at-sea behaviour of seabirds, such as albatrosses and petrels (order Procellariiformes), is difficult to study because they spend most of their time on the ocean and have extremely large ranges. In the early 2000s, behavioural studies of seabirds were dominated by diving patterns of diving birds or spatial studies from satellite telemetry. Recent advances in biologging technologies have opened up new avenues for studying the at-sea behaviour of farranging seabirds in their natural environment. Bio-logging devices are now small enough to be attached to flying seabirds where multiple sensors record data at infrasecond sampling rates. These data can be used to infer, inter alia, body posture, activity (e.g. flapping, takeoff, landing, etc.), magnetic heading and spatial distribution at a resolution that was not previously possible. Bio-logging devices are battery powered and a tradeoff exists between the length of deployments and sampling frequencies, however not a lot of study has been done on what the effect of coarse sampling rates are on data quality. Together with the masses of data that are generated by bio-logging devices, analytical tools have also become available to extract useful metrics from the data. This thesis utilized some of the latest bio-logging technology to study the at-sea behaviour of several procellariiforms, breeding on Marion, Gough and Nightingale Islands, from finescale data. After describing the loggers used and the methods of deployment in Chapter 2, I assess the effect that sampling rates have on metrics derived from GPS loggers in Chapter 3. This was done by sub-sampling GPS tracks recorded at 1-s sampling intervals, showing the effect that different sampling intervals have on metrics, including the total distance travelled and behavioural states derived from path length and turning angles. I show that for larger sampling intervals, the total distance travelled will be underestimated at varying degrees depending on flight sinuosity. By varying sampling rates when estimating behavioural states, I show that moderate (10–30 min) sampling intervals may produce better results. I explore the limitations of low-cost GPS loggers for fine-scale analyses and conclude that specialized loggers are most likely required when sampling at intervals < 1 s. In Chapter 4 I use specialized loggers in the form of tri-axial magnetometer, and video loggers and describe two novel methods to extract roll angles of albatrosses during dynamic soaring flight. Animal body angles are normally extracted by using tri-axial accelerometer data, but their dynamic soaring flight mode inhibits the use of these methods. I show how magnetometer data are independent of dynamic movement and can be used to estimate roll angles of flying seabirds. This method is validated from bird-borne video footage where the horizon is used as a proxy for the bird's roll angle and I describe a method to automatically extract such angles using computer vision techniques. These new methods are then applied to data collected from Wandering Albatrosses Diomedea exulans in Chapter 5, showing how the birds vary their roll angle in response to changing winds. Additionally, flapping flight was identified from patterns in the vertical axis (heave) of a tri-axial accelerometer and I show how Wandering Albatrosses may be flapping more than expected. By coupling flapping and roll angles I show that flapping, on occasion, occur at the upper turn of the dynamic soaring cycle, a period previous thought devoid of flaps. These results also suggest possible sexual differences, where males seem to flap more often than females and limit their take-offs to favourable wind conditions. Lastly, in Chapter 6 I use the same methods as in the previous two chapters to compare the fine-scale flight of six Procellariiformes species breeding on Marion, Gough and Nightingale Islands. I show how these species have varied flight patterns where they respond differently to wind patterns, most likely driving their distribution and eventual foraging areas. As expected, smaller species seem to be more manoeuvrable allowing them to rapidly roll at extreme angles in strong winds while tolerating light winds by increasing the amount of time spent flapping. Breeding location also played a role as birds from the Tristan da Cunha archipelago flapped more often and flew in lighter winds than Marion Island birds. In summary, Chapter 7 discusses how, using a multisensor approach, bio-logging technology can be effectively used to study the fine-scale behaviour of flying seabirds. Each of the loggers have their own limitations and it is important to take these into account when analyzing the data. I describe two new methods for extracting roll angles from dynamic soaring seabirds and show how individuals from several species vary roll angle and flapping flight in response to changing winds. This thesis highlights the varying behavioural strategies that flying seabirds use in the Southern Ocean, showing that individual species and populations may respond differently to changing environmental conditions

Habitat preferences of Phoebetria albatrosses in sympatry and allopatry

Aim: Competition is often proposed to drive niche segregation along multiple axes in speciose communities. Understanding spatial partitioning of foraging areas is particularly important in species that are constrained to a central place. We present a natural experiment examining variation in habitat preferences of congeneric Southern Ocean predators in sympatry and allopatry. Our aim was to ascertain consistency of habitat preferences within species, and to test whether preferences changed in the presence of the congener. Location: Southern Hemisphere. Taxon: Multiple colonies of both species within the genus Phoebetria (sooty albatrosses). Methods: The two Phoebetria albatrosses breed on islands located from ~37–55°S – sooty albatrosses (P. fusca) in the north and light-mantled albatrosses (P. palpebrata) in the south – with sympatric overlap at locations ~46–49°S. We analysed GPS and PTT tracks from 87 individuals and multiple remotely sensed environmental variables using GAMs, to determine and compare the key factors influencing habitat preference for each species at each breeding colony. Results While foraging habitat preferences are consistent in light-mantled albatrosses, there is divergence of preferences in sooty albatrosses depending on whether they are in sympatry with their congener or in allopatry. Main Conclusions This study represents the most comprehensive work on this genus to date and highlights how habitat preferences and behavioural plasticity may influence species distributions under different competitive conditions

The role of wingbeat frequency and amplitude in flight power

Body-mounted accelerometers provide a new prospect for estimating power use in flying birds, as the signal varies with the two major kinematic determinants of aerodynamic power: wingbeat frequency and amplitude. Yet wingbeat frequency is sometimes used as a proxy for power output in isolation. There is, therefore, a need to understand which kinematic parameter birds vary and whether this is predicted by flight mode (e.g. accelerating, ascending/descending flight), speed or morphology. We investigate this using high-frequency acceleration data from (i) 14 species flying in the wild, (ii) two species flying in controlled conditions in a wind tunnel and (iii) a review of experimental and field studies. While wingbeat frequency and amplitude were positively correlated, R2 values were generally low, supporting the idea that parameters can vary independently. Indeed, birds were more likely to modulate wingbeat amplitude for more energy-demanding flight modes, including climbing and take-off. Nonetheless, the striking variability, even within species and flight types, highlights the complexity of describing the kinematic relationships, which appear sensitive to both the biological and physical context. Notwithstanding this, acceleration metrics that incorporate both kinematic parameters should be more robust proxies for power than wingbeat frequency alone

Global assessment of marine plastic exposure risk for oceanic birds

Plastic pollution is distributed patchily around the world’s oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with individual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species

Global assessment of marine plastic exposure risk for oceanic birds

Plastic pollution is distributed patchily around the world's oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with individual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species.B.L.C., C.H., and A.M. were funded by the Cambridge Conservation Initiative’s Collaborative Fund sponsored by the Prince Albert II of Monaco Foundation. E.J.P. was supported by the Natural Environment Research Council C-CLEAR doctoral training programme (Grant no. NE/S007164/1). We are grateful to all those who assisted with the collection and curation of tracking data. Further details are provided in the Supplementary Acknowledgements. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Peer reviewe

Global assessment of marine plastic exposure risk for oceanic birds

Plastic pollution is distributed patchily around the world’s oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with individual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species

The population status, breeding success and foraging ecology of Phoebetria albatrosses on Marion Island

Seabird populations breeding within the Southern Ocean have experienced various threats over the past few decades. Albatrosses are particularly at risk due to several factors, inter alia, accidental bycatch on fishing gear, ingestion of polluted marine debris, invasive predatory species at breeding sites, as well as climate change-induced alterations to ocean circulation patterns. The recent decline in many albatross populations is mainly attributed to incidental fishing mortality, which decreases adult as well as juvenile survival rates and is thus detrimental to these long-lived, low fecundity birds. Recently, changes in fishing regulations to require the use of various mitigation measures have reduced the number of seabirds killed by fishing vessels. However fisheries may still impact seabirds either by direct competition for the same prey, or through ecosystem cascades arising from the removal of predatory fish and squid. Sub-Antarctic islands are important breeding grounds for many seabirds, including albatrosses. Monitoring of seabirds breeding on sub-Antarctic islands is important to detect changes in population dynamics to be able to implement timely conservation measures. Marion Island, the larger of the two Prince Edward Islands, some 2000 km southeast of South Africa, is a breeding site for four albatross species including the sooty (Phoebetria fusca) and light-mantled albatrosses (P. palpebrata). The Prince Edward and Crozet Islands are the only places where both Phoebetria albatrosses breed sympatrically in substantial numbers. Both archipelagos are 46°-47°S, at the southern and northern limit for sooty and light-mantled albatrosses, respectively. At-sea observations and diet studies suggest that sooty albatrosses forage mainly in sub-tropical waters to the north and light-mantled albatross in Antarctic or sub-Antarctic waters to the south. The sooty albatross is listed as Endangered due to recent global population declines whereas the light-mantled albatross is Near-threatened. The only comprehensive study of these species at the Prince Edward Islands was conducted during the late 1970s but annual estimates of breeding populations have been made from 1996 onwards. The previous analysis of these counts, up to 2008, suggested that the sooty albatross population on Marion Island decreased from 1996 to 2008, whereas numbers of light-mantled albatrosses increased over this period. Extending the count series to 2014, trends for both species were reversed, with sooty albatrosses recently increasing and light-mantled albatrosses decreasing. However, the timing of sooty albatross counts is in question as these were done towards the end of the incubation period when many nest failures have already occurred. Breeding success of both Phoebetria albatrosses was estimated during 2013/14 and 2014/15. The success of sooty albatrosses (51% overall) was higher than estimated at Marion Island in the 1970s (19%), but it was still lower than that of a neighbouring colony on Possession Island, Crozet archipelago (65%). The sooty albatross success was however skewed by a sub-colony with a very low 5 breeding success; excluding this sub-colony the breeding success is similar to that of the Crozets. Light-mantled albatross breeding success was the same as past estimates and lower than colonies at Macquarie and Possession Islands. Additional monitoring of a sub-sample of nests within the monitoring colonies was done to determine incubation and brood guard (light-mantled albatross only) shift lengths for both species. The shift lengths and distributions were not significantly different from previous data on Marion Island or other breeding sites

Natural recolonisation of sub-Antarctic Marion Island by Common Diving Petrels Pelecanoides urinatrix

Nocturnal burrow-nesting seabirds are notoriously difficult to study and can go unnoticed for years in remote areas. One of these species is the Common Diving Petrel Pelecanoides urinatrix, which has a circumpolar breeding distribution in the Southern Ocean, including at the sub-Antarctic Prince Edward Islands. At Marion Island, the larger of the two islands, the species was extirpated by cats that were introduced in 1948. The cats were eradicated by 1991, and Common Diving Petrels were discovered in burrows in coastal Poa cookii (Cook’s tussock grass) on a steep south-facing slope in Goodhope Bay during April 2015. Subsequent surveys in October 2015 and February 2016 confirmed breeding over a 1-ha area. In 2019/2020, breeding phenology and success was studied in 36 nests at the same site. Birds called from their burrows from mid-September, laying started in early October, and the first chick was observed on 20 December. Hatching peaked in early January and chicks fledged from the end of February to mid-March. This breeding phenology is similar to that at the neighbouring Crozet Archipelago. Overall nest survival was 46.4 ± 9.2% (mean ± SE; 95% CI: 29.5–64.1%), with most failures happening around hatching time. Further monitoring is needed to assess whether introduced House Mice Mus musculus contributed to the low hatching success. Common Diving Petrels were discovered breeding in other coastal areas, mostly in the south and east of the island. It is unlikely that breeding by this species was overlooked for three decades, suggesting that the elimination of cats allowed Common Diving Petrels to recolonise the island. Il est notoirement reconnu que les oiseaux de mer qui nichent la nuit dans des terriers sont difficiles à étudier et peuvent passer inaperçus pendant des années dans les régions éloignées. L’une de ces espèces est le Puffinure plongeur Pelecanoides urinatrix, qui a une distribution de reproduction circumpolaire dans l’océan austral, comprenant les îles subantarctiques du Prince-Edouard. Sur l’île de Marion, la plus grande des deux îles, cette espèce a été extirpée par des chats introduits en 1948. Les chats ont été complètement éradiqués en 1991 et au cours du mois d’avril 2015, des Puffinures plongeurs ont été découverts dans des terriers situés dans d’épaisses touffes d’herbes Poa cookii (tussock) de la zone côtière, sur une pente raide orientée au sud de la baie de Goodhope. Des recherches complémentaires menées en octobre 2015 et février 20216 ont confirmé la zone de reproduction sur une superficie d’environ 1 ha. La phénologie et le succès de reproduction de 36 nids localisés sur le même site ont été étudiés sur la période 2019-2020. Les oiseaux ont crié depuis leur terrier à partir de mi-septembre, la ponte a commencé début octobre et le premier poussin a été observé le 20 décembre. Le pic d’éclosion a eu lieu début janvier et les poussins se sont envolés de fin février à mi-mars. Cette phénologie de reproduction est similaire à celle observée sur l’archipel voisin de Crozet. Le taux de survie globale des nichées était de 46.4 ± 9.2% (σ; IC95%: 29.5–64.1%), la plupart des échecs se produisant autour de la période d’éclosion. Une surveillance complémentaire est nécessaire pour estimer si les souris domestiques Mus musculus introduites jouent un rôle dans le faible succès d’éclosion. Des zones de reproduction du Puffinure plongeur ont été découvertes dans d’autres zones côtières, principalement au sud et à l’est de l’île. Il est peu probable que la reproduction de cette espèce ait été négligée pendant trois décennies, ce qui laisse supposer que l’élimination des chats a permis au Puffinure plongeur de recoloniser l’île

Avian pox in seabirds on Marion Island, southern Indian Ocean

Albatrosses are among the most threatened groups of seabirds with the main land-based threats being alien invasive species, human disturbance and habitat degradation. Disease outbreaks in Antarctic and sub-Antarctic seabird populations are uncommon, but in the past few decades there has been an increase in reported cases. The sub-Antarctic Prince Edward Islands (46°S, 37°E) in the south-western Indian Ocean provide breeding grounds for many seabird species, including 44% of all wandering albatrosses (Diomedea exulans L.). In 2015, five wandering albatrosses and two penguins (Eudyptes chrysocome Forster and Aptenodytes patagonicus Miller) with pox-like lesions were observed on Marion Island, the larger of the two Prince Edward Islands. Despite intensive study of the wandering albatross population since the 1980s, the only previous records of such lesions are one case in 2006 and another in 2009 in white-chinned petrels (Procellaria aequinoctialis L.). Molecular and phylogenetic analysis of tissue samples from two albatross chicks confirmed the presence of avian pox virus (Avipoxvirus). This highlights the need for research into the diseases present on sub-Antarctic islands, for strict controls to limit the risk of accidental introduction of diseases through human activities and the need for effective conservation measures in the event of an outbreak.The South African Department of Environmental Affairs, through the South African National Antarctic Programme (SANAP), the National Research Foundation and the University of Cape Town.http://journals.cambridge.org/action/displayJournal?jid=ANS2018-08-30hj2018Mammal Research InstituteZoology and Entomolog

A survey of Great-winged Petrels Pterodroma macroptera breeding at sub-Antarctic Marion Island and a revised global population estimate

Although burrow-nesting petrels are the most abundant group of seabirds in the Southern Ocean, their global populations are poorly known,&nbsp; because most species breed on remote islands. For example, there are no accurate estimates for Great-winged Petrel Pterodroma macroptera populations at any of its major breeding sites. Moreover, current global population estimates for Great-winged Petrels of approximately 1.5 million birds include counts of the closely related Grey-faced Petrel P. gouldi, which is now recognised as a different species. On sub-Antarctic Marion Island, Great-winged Petrel burrows found within random strip transects were counted and then burrow densities were extrapolated by GIS-derived habitat attributes to generate an island-wide burrow estimate (33 000 burrows). Burrow occupancy rates at the start of incubation averaged 48 ± 29% (range 10–94%) during one-off surveys at ten sites around the island, and repeat surveys found at least 42% of burrows were occupied by breeders. This suggests there were approximately 14 000 occupied burrows (95% CI 9 500–18 500) on Marion Island in 2015. Collating data from other breeding sites suggests that the global breeding population is perhaps 100 000–150 000 pairs (400 000–600 000 birds). Estimation de la population de Pétrel Noirs se reproduisant sur l’île sub-Antarctique Marion et révision de la population mondiale Bien que les pétrels reproduction hypopgée représentent le groupe le plus abondant des oiseaux de mer de l’Océan Austral, leurs abondances&nbsp; réelles sont rarement connues car la plupart des espèces se reproduisent sur les îles isolées. Par exemple, il n’existe aucune estimation précise des populations de Pétrel Noir Pterodroma macroptera sur aucune de leurs colonies majeures de reproduction. De plus, la population globale qui est actuellement estimée à 1.5 million d’oiseaux, inclut également les populations de Pétrel à face grise P. gouldi, espèce qui est maintenant reconnue comme une espèce à part entière. Un comptage des terriers de Pétrel Noirs sur l’île sub-Antarctique Marion a été réalisé par la méthode de transects choisis aléatoirement. La densité globale pour l’île a ensuite été extrapolée par SIG en tenant compte des caractéristiques des habitats potentiels de l’île (33 000 terriers). En début d’incubation, l’occupation des nids observée sur 10 sites tout autour de l’île était en moyenne de 48 ± 29% (intervalle 10–94%). Des contrôles répétés ont montré que 42% de ces terriers étaient occupés par des oiseaux reproducteurs. Cette estimation suggère un nombre de terriers occupés d’environ 14 000 (95% intervalle de confiance 9 500–18 500) pour l’île Marion en 2015. Additionné aux&nbsp; données des autres sites de reproduction, cela suggère une population mondiale estimée à 100 000–150 000 couples reproducteurs (400 000–600 000 oiseaux). Keywords: burrow-nesting petrel, Grey-faced Petrel P. gouldi, nest surveys, random transects, seabird