ORCID Profile
0000-0001-7042-3461
Current Organisations
Universität Wien
,
University of Vienna
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Publisher: MDPI AG
Date: 04-12-2021
DOI: 10.3390/BIRDS2040032
Abstract: When different introduced species across trophic levels (parasite, predator) invade island systems, they may pose significant threats to nesting birds. In this study, we measure nesting height and infer causes of offspring mortality in the critically endangered Medium Tree Finch (Camarhynchus pauper), an island endemic restricted to Floreana Island on the Galápagos Archipelago. Considering all nests at which a male built a nest, sang and attempted to attract a female (n = 222 nests), only 10.4% of nests produced fledglings (5% of nests had total fledging success, 5.4% of nests had partial fledging success). Of the 123 nests chosen by a female, 18.7% produced fledglings and of 337 eggs laid, 13.4% produced fledglings. Pairing success was higher for older males, but male age did not predict nesting success. All nests with chicks were infested with avian v ire fly larvae (Philornis downsi). We attributed the cause of death to avian v ire fly if chicks were found dead in the nest with fly larvae or pupae (45%) present. We inferred avian (either Asio flammeus galapagoensis or Crotophaga ani) predation (24%) if the nest was empty but dishevelled and black rat (Rattus rattus) predation (20%) if the nest was empty but undamaged. According to these criteria, the highest nests were depredated by avian predators, the lowest nests by rats, and intermediate nests failed because of avian v ire fly larvae. In conclusion, there is no safe nesting height on Floreana Island under current conditions of threats from two trophic levels (introduced parasitic dipteran, introduced mammalian/avian predators with Galápagos Short-Eared Owls being the only native predator in the system).
Publisher: The Raptor Research Foundation, Inc.
Date: 19-12-2022
DOI: 10.3356/JRR-22-68
Publisher: Elsevier BV
Date: 11-2021
Publisher: Springer Science and Business Media LLC
Date: 20-11-2022
DOI: 10.1007/S00436-021-07350-1
Abstract: Understanding the range and behaviour of an invasive species is critical to identify key habitat areas to focus control efforts. Patterns of range use in parasites can differ temporally, across life stages and between sexes. The invasive avian v ire fly, Philornis downsi , spends the larval stage of its life within bird nests, feeding on developing nestlings and causing high levels of mortality and deformation. However, little is known of the ecology and behaviour of the non-parasitic adult fly life stage. Here, we document sex-specific temporal and spatial patterns of abundance of adult avian v ire flies during a single Darwin’s finch breeding season. We analyse fly trapping data collected across 7 weeks in the highlands ( N = 405 flies) and lowlands ( N = 12 flies) of Floreana Island (Galápagos). Lowland catches occurred later in the season, which supports the hypothesis that flies may migrate from the food-rich highlands to the food-poor lowlands once host breeding has commenced. Fly abundance was not correlated with host nesting density (oviposition site) but was correlated with distance to the agricultural zone (feeding site). We consistently caught more males closer to the agricultural zone and more females further away from the agricultural zone. These sex differences suggest that males may be defending or lekking at feeding sites in the agricultural zone for mating. This temporal and sex-specific habitat use of the avian v ire fly is relevant for developing targeted control methods and provides insight into the behavioural ecology of this introduced parasite on the Galápagos Archipelago.
Publisher: Springer Science and Business Media LLC
Date: 04-08-2021
DOI: 10.1038/S41598-021-94996-7
Abstract: In invasive parasites, generalism is considered advantageous during the initial phase of introduction. Thereafter, fitness costs to parasites, such as host-specific mortality, can drive parasites towards specialism to avoid costly hosts. It is important to determine changes in host specificity of invasive populations to understand host-parasite dynamics and their effects on vulnerable host populations. We examined changes in mortality in the introduced avian v ire fly ( Philornis downsi ) (Diptera: Muscidae), a generalist myasis-causing ectoparasite, between 2004 and 2020 on Floreana Island (Galápagos). Mortality was measured as the proportion of immature larvae found upon host nest termination. Over the time period, the avian v ire fly was most abundant and had low mortality in nests of the critically endangered medium tree finch ( Camarhynchus pauper ) and had the highest mortality in nests of hybrid tree finches ( Camarhynchus spp.). Low larval mortality was also found in small tree ( Camarhynchus parvulus) and small ground finch ( Geospiza fuliginosa) nests. Selection could favour avian v ire flies that select medium tree finch nests and/or avoid hybrid nests. Overall, the finding of differences in avian v ire fly survival across host species is parsimonious with the idea that the introduced fly may be evolving towards host specialisation.
Publisher: Springer Science and Business Media LLC
Date: 18-07-2023
DOI: 10.1038/S41598-023-38493-Z
Abstract: Urbanisation is occurring around the world at a rapid rate and is generally associated with negative impacts on bio ersity at local, regional, and global scales. Examining the behavioural response profiles of wildlife to urbanisation helps differentiate between species that do or do not show adaptive responses to changing landscapes and hence are more or less likely to persist in such environments. Species-specific responses to urbanisation are poorly understood in the Southern Hemisphere compared to the Northern Hemisphere, where most of the published literature is focussed. This is also true for raptors, despite their high ersity and comparably high conservation concern in the Southern Hemisphere, and their critical role within ecosystems as bioindicators of environmental health. Here, we explore this knowledge gap using community science data sourced from eBird to investigate the urban tolerance of 24 Australian raptor species at a continental scale. We integrated eBird data with a global continuous measure of urbanisation, artificial light at night (ALAN), to derive an urban tolerance index, ranking species from positive to negative responses according to their tolerance of urban environments. We then gathered trait data from the published literature to assess whether certain traits (body mass, nest substrate, habitat type, feeding guild, and migratory status) were associated with urban tolerance. Body size was negatively associated with urban tolerance, as smaller raptors had greater urban tolerance than larger raptors. Out of the 24 species analysed, 13 species showed tolerance profiles for urban environments (positive response), and 11 species showed avoidance profiles for urban environments (negative response). The results of this study provide impetus to conserve native habitat and improve urban conditions for larger-bodied raptor species to conserve Australian raptor ersity in an increasingly urbanised world.
Publisher: Springer Science and Business Media LLC
Date: 07-09-2021
DOI: 10.1007/S00114-021-01745-X
Abstract: Urbanisation is proceeding at an alarming rate which forces wildlife to either retreat from urban areas or cope with novel stressors linked to human presence and activities. For ex le, urban stressors like anthropogenic noise, artificial light at night and chemical pollution can have severe impacts on the physiology of wildlife (and humans), in particular the immune system and antioxidant defences. These physiological systems are important to combat and reduce the severity of parasitic infections, which are common among wild animals. One question that then arises is whether urban-dwelling animals, whose immune and antioxidant system are already challenged by the urban stressors, are more susceptible to parasitic infections. To assess this, we studied nestlings of Eurasian kestrels ( Falco tinnunculus ) in Vienna, Austria, during 2015 and 2017. We measured biomarkers of innate immune function, oxidative stress and body mass index and ectoparasite infection intensity in 143 nestlings (from 56 nests) along an urban gradient. Nestlings in more urbanised areas had overall fewer ectoparasites, lower haemolysis (complement activity) and lower body mass index compared to nestlings in less urbanised areas. None of the other immune or oxidative stress markers were associated with the urban gradient. Despite some non-significant results, our data still suggest that kestrel nestlings experience some level of reduced physiological health, perhaps as a consequence of exposure to more urban stressors or altered prey availability in inner-city districts even though they had an overall lower ectoparasite burden in these heavily urbanised areas.
Publisher: Springer Science and Business Media LLC
Date: 09-08-2021
DOI: 10.1038/S41598-021-95011-9
Abstract: Local weather conditions may be used as environmental cues by animals to optimize their breeding behaviour, and could be affected by climate change. We measured associations between climate, breeding phenology, and reproductive output in greylag geese ( Anser anser ) across 29 years (1990–2018). The birds are in idually marked, which allows accurate long-term monitoring of life-history parameters for all pairs within the flock. We had three aims: (1) identify climate patterns at a local scale in Upper Austria, (2) measure the association between climate and greylag goose breeding phenology, and (3) measure the relationship between climate and both clutch size and fledging success. Ambient temperature increased 2 °C across the 29-years study period, and higher winter temperature was associated with earlier onset of egg-laying. Using the hatch-fledge ratio, average annual temperature was the strongest predictor for the proportion of fledged goslings per season. There is evidence for an optimum time window for egg-laying (the earliest and latest eggs laid had the lowest fledging success). These findings broaden our understanding of environmental effects and population-level shifts which could be associated with increased ambient temperature and can thus inform future research about the ecological consequences of climate changes and reproductive output in avian systems.
No related grants have been discovered for Petra Sumasgutner.