Biology subjects

Descamps, S.

Publications and source records attributed to Descamps, S..

5 recordsLinked to original sources

bioRxiv2026

Time-lagged causal inference corroborates presumed drivers of North Atlantic seabird ecology

Disentangling causation from correlation is the foundation of the scientific method. Yet, growing evidence suggests that much observational ecology research has not correctly made this distinction due to inappropriate statistical modelling and unappreciated time-delays. Here, we apply time-lagged causal inference techniques to assess the drivers of seabird declines, using multi-decadal North Atlantic seabird data across the behaviour, mass, survival, reproduction and population size of two species ecology (Atlantic puffin, Fratercula arctica, and black-legged kittiwake, Rissa tridactyla). We demonstrate that both climate and anthropogenic activity can suppress breeding success and cause population declines. Moreover, population size is specifically impacted by delayed recruitment effects where both species decline after a lag corresponding to their estimated age of first reproduction. These North Atlantic seabirds are therefore at risk from future environmental and anthropogenic changes, as time-delays may result in populations already on an extinction trajectory prior to changes being detectable in their abundance.

ecology↗

bioRxiv2026

Multiple Introductions of Highly Pathogenic Avian Influenza Viruses into the High Arctic: Svalbard and Jan Mayen, 2022 - 2025

Between 2022 and 2025, highly pathogenic avian influenza viruses (HPAIVs) of clade 2.3.4.4b, including four distinct H5 Eurasian (EA) genotypes, were detected in wild birds and mammals in the Svalbard Archipelago and on the island of Jan Mayen. We describe their epidemiology and genomic characteristics to improve understanding of HPAIV occurrence and transmission in the High Arctic. The initial cases in 2022 occurred during summer and involved a glaucous gull (Larus hyperboreus) and great skuas (Stercorarius skua) on Svalbard and Jan Mayen, representing the first detections of HPAIVs in the High Arctic. Three HPAIV genotypes were identified: EA-2020-C (H5N1), EA-2021-AB (H5N1), and EA-2021-I (H5N5). In 2023, HPAIVs were detected in a broader range of bird species, and retrospectively in an Atlantic walrus reported by another research group (Odobenus rosmarus rosmarus). Genotypes identified in 2023 were EA-2020-C (H5N1), EA-2021-I (H5N5), and EA-2022-BB (H5N1). No cases were reported in 2024. In 2025, EA-2021-I (H5N5) was detected in Arctic foxes (Vulpes lagopus) on Svalbard, without preceding detections in wild birds. The foxes exhibited neurological symptoms, and necropsy of one individual revealed the presence of feathers in its stomach. All sequenced viruses from the Arctic foxes uniquely carried the combination of PB2-E627K and PB1-H115Q, which is associated with mammalian adaptation. The detection of multiple genotypes indicates repeated and independent introductions of HPAIVs into these regions. The co-circulation of genetically distinct virus strains in areas of high bird density further suggests that Arctic breeding grounds may facilitate local viral amplification, reassortment, and subsequent dissemination along migratory flyways, including transcontinental spread. Data summaryThe authors confirm all supporting data, code and protocols have been provided within the article or through supplementary data files. Influenza A whole genome sequences generated through this study are available under the GISAID accession numbers found in Table 1. All genome sequences and associated metadata supporting the findings of this study can be accessed through the persistent digital object identifier https://doi.org/10.55876/gis8.260211rq. O_TBL View this table: org.highwire.dtl.DTLVardef@15e1921org.highwire.dtl.DTLVardef@c3e91borg.highwire.dtl.DTLVardef@1fcfe78org.highwire.dtl.DTLVardef@a69606org.highwire.dtl.DTLVardef@c36c74_HPS_FORMAT_FIGEXP M_TBL O_FLOATNOTable 1.C_FLOATNO O_TABLECAPTIONDetections of highly pathogenic avian influenza virus (HPAIV) in wild birds and mammals sampled in the Svalbard Archipelago and on Jan Mayen from January 1st, 2022, to August 31st, 2025. C_TABLECAPTION C_TBL

microbiology↗

bioRxiv2025

Variability in foraging ranges of snow petrels and implications for breeding distribution and use of stomach-oil deposits as proxies for paleoclimate

BackgroundBreeding pelagic seabirds feed over wide areas. Their diet and space use can therefore provide proxies for otherwise be difficult to observe environmental conditions but interpretation of these proxies requires knowledge of foraging range. Antarctic sea ice regulates global climate, but a paucity of data on its past extent causes uncertainty in climate reconstruction and prediction. Deposits of stomach oils, produced defensively by snow petrels Pagodroma nivea (near-obligate sea-ice foragers), reflect sea ice conditions, sometimes over tens of millennia, but spatial interpretation of these biological archives is hampered by lack of data on foraging range, and how this varies seasonally, among colonies and with sex. MethodsWe tracked 34 and 60 snow petrels using light-based geolocators and GPS loggers, respectively to estimate foraging ranges at three colonies located 180-200 km inland in Dronning Maud Land. We tested whether foraging latitude is associated with ice edge latitude, estimated via satellite remote sensing. We then projected potential foraging ranges for all known colonies on the study area to reexamine assumptions made in paleoclimate studies. ResultsDuring most breeding stages, and across breeding seasons, core home ranges were centred approximately 2{degrees} south of the outer sea-ice edge and tracked this habitat as it receded during the spring melt. Females were approximately 7% lighter than males but foraged at similar distances and in similar areas. Foraging ranges differed little between colonies but substantially between breeding stages. For example, median range was [~]1,400 km during the pre-laying exodus vs. [~]550 km during brood-guard. ConclusionsSnow petrel stomach-oil deposits potentially integrate environmental conditions over greater and more seasonally variable areas than previously assumed, probably with a bias towards conditions in the outer Marginal Ice Zone during the early summer when stomach oil deposition due to nest competition is likely greatest. Projected potential home ranges of snow petrel colonies in the western Weddell Sea suggest that breeding is limited by access to foraging habitat, such as coastal polynyas. We hypothesise that as sea ice fluctuated over previous glacial-interglacial cycles, this also regulated breeding distribution across the region.

ecology↗

bioRxiv2022

Climate change in the Arctic: testing the poleward expansion of ticks and tick-borne diseases

Climate change is most strongly felt in the polar regions of the world, with significant impacts for the species that live in these extreme environments. The arrival of parasites and pathogens from more temperate areas may become a significant problem for these populations, but current observations of parasite presence often lack a historical reference of prior absence. Observations in the high Arctic of the seabird tick Ixodes uriae suggested that this species recently expanded its range poleward. As this tick can have a direct impact on the breeding success of its seabird hosts and is vector of many potential disease agents, including Lyme disease spirochaetes, its presence and origin are important elements for predicting its impact on polar seabird populations. Here, we use population genetic data and host serology to test the hypothesis that Ixodes uriae has recently expanded into the Svalbard archipelago. Both Black-legged kittiwakes (Rissa tridactyla) and Thick-billed murres (Uria lomvia) were captured in Kongsfjorden, Spitsbergen and sampled for ticks and blood. Collected ticks were genotyped using microsatellite markers and population genetic analyses were carried out using data from 14 additional seabird colonies distributed across the ticks northern distribution. In contrast to predictions based on a recent expansion, the Spitsbergen population showed high genetic diversity and significant differentiation from the more southern populations, suggesting long-term population isolation. Host serology also demonstrated a high exposure rate to Lyme disease spirochaetes (Bbsl). Targeted PCR on tick DNA extracts and sequencing identified the presence of Borrelia garinii in a Spitsbergen tick, confirming seabird exposure and demonstrating the presence of Lyme disease bacteria in the high Arctic for the first time. Taken together, results contradict the notion that Ixodes uriae has recently expanded into the high Arctic region. Rather, this tick has likely been present for some time, maintaining relatively high population sizes and an endemic transmission cycle of Bbsl spirochaetes. Close future observations of population infestation/infection rates will now be necessary to relate epidemiological changes to ongoing climate modifications. Author summaryThe climate in the Arctic is rapidly changing, and with it, the flora and fauna that live there. These new environmental conditions can favor the establishment of invasive species, including novel parasites and pathogens. Here, we use population genetic data and host serology to examine whether recent observations of ticks infesting breeding seabirds in the high Arctic represent a poleward expansion of the parasite. Contrary to predictions, tick populations showed no evidence of a recent colonization of the region. Ticks have likely be present for a relatively long time, maintaining high local diversity despite harsh environmental conditions and vectoring infectious agents among breeding birds. Indeed, we demonstrate the presence of Lyme disease spirochaetes in the high Arctic for the first time, with bacterial DNA found in one of the sampled ticks and seabird serology demonstrating high exposure to this pathogen. This Lyme disease agent has therefore likely been established in the region and circulating at low frequency between seabirds and ticks for some time.

ecology↗

bioRxiv2020

Complex population structure of the Atlantic puffin revealed by whole genome analyses

The factors underlying gene flow and genomic population structure in vagile seabirds are notoriously difficult to understand due to their complex ecology with diverse dispersal barriers and extensive periods at sea. Yet, such understanding is vital for conservation management of seabirds that are globally declining at alarming rates. Here, we elucidate the population structure of the Atlantic puffin (Fratercula arctica) by assembling its reference genome and analyzing genome-wide resequencing data of 72 individuals from 12 colonies. We identify four large, genetically distinct clusters, observe isolation-by-distance between colonies within these clusters, and obtain evidence for a secondary contact zone. These observations disagree with the current taxonomy, and show that a complex set of contemporary biotic factors impede gene flow over different spatial scales. Our results highlight the power of whole genome data to reveal unexpected population structure in vagile marine seabirds and its value for seabird taxonomy, evolution and conservation.

genomics↗