Biology subjects

Loonen, M. J. J. E.

Publications and source records attributed to Loonen, M. J. J. E..

4 recordsLinked to original sources

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↗

bioRxiv2024

Diel and seasonal rhythmicity in activity and corticosterone in an Arctic migratory herbivore: A multifaceted approach

Birds that migrate from temperate areas to the Arctic to breed lose their strongest Zeitgeber of circadian organization when they cross the Arctic circle in spring: the 24h light-dark cycle. Under continuous daylight, diverse behavioural and physiological patterns have been detected in both free-ranging and laboratory animals. To better understand the evolution of plasticity in circadian clocks, it is essential to study behavioural and physiological rhythmicity in the context of a species ecology. Employing a multifaceted approach, which included wildlife cameras, accelerometers, and non-invasive sampling of hormone metabolites, we investigated activity patterns and corticosterone rhythmicity in a migratory herbivore, the barnacle goose (Branta leucopsis), during its Arctic breeding season in Svalbard. We found that females showed a combination of both ultradian and diel rhythmicity in nest recesses and sleep during incubation. In both parents, these rhythms in activity continued also during the gosling rearing period. During moult, many geese aligned activity with the tidal rhythm. Barnacle geese showed weak diel rhythmicity in excreted corticosterone metabolites. This suggests that while Arctic geese may adopt an alternative Zeitgeber during the Arctic summer to maintain a diel rhythm, ultradian rhythmicity remains essential, allowing the geese to flexibly adjust their rhythms to environmental conditions.

ecology↗

bioRxiv2024

Dads on duty: First account of nest sitting in barnacle ganders

In most Anseriformes (ducks, geese and swans) only females are known to incubate. Here we scientifically describe, indicidents of male nest sitting in barnacle geese (Branta leucopsis) as a form of paternal care of nest attendance. Based on pictures from wildlife cameras we identified males, which sat on their nests when their mates took incubation recesses. Wildlife cameras were placed at nests of which either the male or female was fitted with a GPS neck collar in the year prior, which aided with identifying individual birds on the nest. To attach transmitters, some geese were caught while defending their nests, thus we may have unintentionally selected bolder males which defended their nests more aggressively and were easier to catch. Nest sitting occurred relatively frequent, i.e. in 6/15 individuals. Our results show that males with collars were more likely to nest sit, but this does not deflect from the fact this behaviour exists in geese. In the course of this finding we discuss several possible functions of this behaviour, i.e. against raiding of nests by aerial predators, thermal control of nest temperature, and intraspecific brood parasitism. At this time we cannot demonstrate a possible function, as chances of successful hatching were not increased in nest-sitting males and we lack sample size for more in depth analyses. Lastly, we argue that male incubation is misleading in the waterfowl literature, as it is truly justified for only two species, the black swan (Cygnus atratus) and black-bellied whistling duck (Dendrocygna autumnalis).

animal behavior and cognition↗

bioRxiv2023

Long-term herbivore removal experiments reveal different impacts of geese and reindeer on vegetation and ecosystem CO2-fluxes in high-Arctic tundra

O_LIGiven the current and anticipated rates of global change, with associated shifts in herbivore population densities, understanding the role of different herbivores in shaping ecosystem structure and processes is critical for predicting ecosystem responses. Here, we examined the controls exerted by migratory geese and resident, non-migratory ungulates, two dominating yet functionally contrasting herbivores, on the rapidly warming Arctic tundra. C_LIO_LIWe collected vegetation and ecosystem carbon flux data at peak plant growing season in the two longest running herbivore removal experiments in high-Arctic Svalbard. Herbivore exclosures had been set up independently in a wet habitat utilised by barnacle geese (Branta leucopsis) in summer and in mesic-to-dry habitats utilised by wild reindeer (Rangifer tarandus platyrhynchus) year-round. C_LIO_LIExcluding geese produced vegetation state transitions from heavily grazed, moss-dominated (4 g m-2 dry weight of live aboveground vascular plants) to ungrazed, graminoid-dominated (60 g m-2; after 4-yr exclusion) and then horsetail-dominated (150 g m-2; after 15-yr exclusion) tundra. This caused large increases in vegetation carbon and nitrogen pools, dead biomass and moss-layer depth. Modifications in nitrogen concentrations and carbon-to-nitrogen ratios of vegetation and soil suggested overall slower nutrient cycling rates in the short-term absence of geese. Long-term goose removal quadrupled the net ecosystem carbon sequestration by increasing gross ecosystem photosynthesis more than ecosystem respiration. C_LIO_LIExcluding reindeer for 21 years also produced detectable, but weaker, increases in live and dead biomass, vegetation carbon and nitrogen pools, moss-layer depth and ecosystem respiration. Yet, reindeer removal did not alter the chemistry of either vegetation or soil, nor net ecosystem carbon sequestration. C_LIO_LIOur findings suggest that, though both herbivores were key drivers of ecosystem structure and processes, localised effects of geese, highly concentrated in space and time, are larger than those exerted by more widely dispersed reindeer. We illustrate that the impacts of herbivory across the tundra landscape are contingent on the habitat utilised for foraging, its sensitivity, the exerted grazing pressure, and herbivore characteristics. Our results underscore the conspicuous heterogeneity in how Arctic herbivores control ecosystem functioning, with important implications under current and future global change. C_LI

ecology↗