Biology subjects

Courbin, N.

Publications and source records attributed to Courbin, N..

4 recordsLinked to original sources

bioRxiv2023

Flight heights of Scopoli s shearwaters Calonectris diomedea in the context of offshore wind farm developments

Seabird face new risks through collisions with offshore wind turbines. Wind energy projects are emerging in the Mediterranean Sea, and unbiased knowledge on seabird flight altitudes are scarce in this area. Indeed, previous flight height observations were carried out from boats during daytime, and only in good weather conditions. We measured flight heights of 13 Scopolis shearwaters, Calonectris diomedea, one of the three endemic shearwater species in the Mediterranean, using highly precise barometric data loggers. The birds were equipped at the largest French colony of Scopolis shearwater in the Marseille archipelago. Birds from this location routinely visit forthcoming wind farm areas, within 50 km of their breeding site. We found that Scopolis shearwaters flew at very low altitudes with a mean flight height of 1.8 {+/-} 2.7 m ({+/-} SD) above sea level. Birds therefore rarely (<0.02%) flew within the vertical envelop of collision risk with wind turbines. Ours results are coherent with field observations and the dynamic soaring flight technique used by shearwaters. Nevertheless, collision risk may increase following behavioural modifications close to wind turbines.

ecology↗

bioRxiv2023

Strong breeding colony fidelity in northern gannets following High Pathogenicity Avian Influenza Virus (HPAIV) outbreak

High pathogenicity avian influenza virus (HPAIV) caused the worst seabird mass-mortalities on record in Europe across 2021-2022. The northern gannet (Morus bassanus) was one of the most affected species, with tens of thousands of casualties in the northeast Atlantic between April-September 2022. Disease outbreaks can drastically modify the movement ecology of animals and diminish spatial consistency, thereby increasing the potential for disease transmission. To detect potential changes in movement behaviour, we GPS-tracked breeding adults following the initial HPAIV outbreak, at three of the largest gannet breeding colonies where major mortality of adults and chicks occurred (Bass Rock, Scotland, UK; Grassholm, Wales, UK; Rouzic island, Brittany, France). Crucially, GPS-tracked birds remained faithful to their breeding sites and did not prospect other breeding colonies. They performed regular foraging trips at sea, similar to their behaviour before the outbreak. Gannet foraging effort was nonetheless lower than in 2019, thus surviving birds may have benefited from reduced intra- and interspecific food competition. Breeding colony fidelity of adult northern gannets following HPAIV mass-mortalities suggests limited long-term capacity to virus spread, which may contrast with the behaviour of adults during the disease outbreak, or with that of younger individuals.

ecology↗

bioRxiv2022

Accounting for central place foraging constraints in habitat selection studies

Habitat selection studies contrast the actual space use with the expected use under the null hypothesis of no preference (hereafter neutral use). Neutral use is most often assimilated to the relative abundance of the different habitat types. This generates a considerable bias when studying habitat selection by foragers that perform numerous back and forth to a central place (CP). Indeed, the increased space use close to the CP with respect to distant places reflects a mechanical effect rather than a true preference for the closest habitats. Yet, correctly estimating habitat selection by CP foragers is of paramount importance for a better understanding of their ecology and efficiency of conservation actions. We show that (1) including the distance to the CP as a covariate in unconditional Resource Selection Functions (RSFs), as did in several studies, is quite inefficient to correct for the bias. Bias can be eliminated only by contrasting the actual use distribution to an appropriate neutral distribution that takes the CP forager behavior into account. (2) The need to specify such an appropriate neutral use distribution can be bypassed by relying on a conditional RSF, where the neutral use is assessed locally without reference to the CP.

ecology↗

bioRxiv2017

Zebra diel migrations reduce encounter risk with lions over selection for safe habitats

Diel migrations (DMs) undertaken by prey to avoid visual predators during the day have been demonstrated in many taxa in aquatic ecosystems. We reveal that zebras in Hwange National Park (Zimbabwe) employ a similar anti-predator strategy. Zebras forage near waterholes during the day but move away from them at sunset. We demonstrate that this DM, occurring over a few km, dramatically reduces their night-time risk of encountering lions, which generally remain close to waterholes. By contrast, zebra changes in night-time selection for vegetation types marginally reduced their risk of encountering lions. This may arise from a trade-off between encounter risk and vulnerability across vegetation types, with zebras favouring low vulnerability once DM has reduced encounter risk. In summary, here we (1) quantify the effect of a predator-induced DM in a terrestrial system on the likelihood of encountering a predator, (2) distinguish the effects of the DM from those related to day/night changes in selection for vegetation types. We discuss how revealing how prey partition their risk between predator encounter risk and habitat-driven vulnerability is likely critical to understand the emergence of anti-predator behavioural strategies.

ecology↗