A natural antipredation experiment: predator control and reduced sea ice increases colony size in a long-lived duck

Anthropogenic impact on the environment and wildlife are multifaceted and far-reaching. On a smaller scale, controlling for predators has been increasing the yield from local natural prey resources. Globally, human-induced global warming is expected to impose severe negative effects on ecosystems, an effect that is expected to be even more pronounced in the scarcely populated northern latitudes. The clearest indication of a changing Arctic climate is an increase in both air and ocean temperatures leading to reduced sea ice distribution. Population viability is for long-lived species dependent on adult survival and recruitment. Predation is the main mortality cause in many bird populations, and egg predation is considered the main cause of reproductive failure in many birds. To assess the effect of predation and climate, we compared population time series from a natural experiment where a trapper/down collector has been licensed to actively protect breeding common eiders Somateria mollissima (a large seaduck) by shooting/chasing egg predators, with time series from another eider colony located within a nature reserve with no manipulation of egg predators. We found that actively limiting predator activity led to an increase in the population growth rate and carrying capacity with a factor of 3–4 compared to that found in the control population. We also found that population numbers were higher in years with reduced concentration of spring sea ice. We conclude that there was a large positive impact of human limitation of egg predators, and that this lead to higher population growth rate and a large increase in size of the breeding colony. We also report a positive effect of warming climate in the high arctic as reduced sea-ice concentrations was associated with higher numbers of breeding birds. Carrying capacity, climate change, high Arctic, population growth rate, predator effects, sea ice, Svalbard.A natural antipredation experiment: predator control and reduced sea ice increases colony size in a long-lived duckpublishedVersio

Differences in speciation progress in feather mites (Analgoidea) inhabiting the same host: the case of Zachvatkinia and Alloptes living on arctic and long-tailed skuas

Recent molecular phylogenetic analyses have revealed that some apparently oligoxenous feather mite species are in fact monoxenous cryptic species with little morphological differentiation. In this study we analyzed two species, Zachvatkinia isolata (Avenzoariidae) and Alloptes (Sternalloptes) stercorarii (Alloptidae) which prefer different parts of the plumage of two sister species of birds: arctic skua (Stercorarius parasiticus) and long-tailed skua (S. longicaudus) breeding on tundra in the High Arctic archipelago of Svalbard. Given that there are no reports about hybridization events between the host species, we expected that both skuas would have a species-specific acarofauna. The genetic distances among DNA-barcode sequences (COI and 28S rDNA), phylogenetic tree topologies, and haplotype networks of the COI sequences of mites suggested extensive gene flow in Z. isolata between and within populations inhabiting both skua species, whereas the Alloptes populations were host specific and sufficiently genetically separated as to warrant species-level status. The discrepancy in the genetic structure of Alloptes and Zachvatkinia populations suggests frequent but transient contacts between the two skua species in which the probability of mite exchange is much higher for Zachvatkinia, which is present in high numbers and inhabits exposed parts of primary flight feathers, than for the less abundant Alloptes that lives primarily in more protected and inaccessible parts of the plumage. We discuss the possible nature of these contacts between host species and the area(s) where they might take place. The star-like structures in the haplotype network as well as high haplotype diversity and low nucleotide diversity observed in Z. isolata are concordant with the known dispersal strategy of feather mites: vertical colonization of new host individuals followed by rapid growth of founder populations

Impacts of a warming climate on concentrations of organochlorines in a fasting high arctic marine bird: Direct vs. indirect effects?

The present study examined how climate changes may impact the concentrations of lipophilic organochlorines (OCs) in the blood of fasting High Arctic common eiders (Somateria mollissima) during incubation. Polychlorinated biphenyls (PCBs), 1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p′-DDE), hexachlorobenzene (HCB) and four chlordane compounds (oxychlordane, trans-chlordane and trans- and cis-nonachlor) were measured in females at chick hatching (n = 223) over 11 years (2007–2017). Firstly, median HCB and p,p′-DDE concentrations increased ~75 % over the study period, whereas median chlordane concentrations doubled (except for oxychlordane). PCB concentrations, in contrast, remained stable over the study period. Secondly, both body mass and clutch size were negatively associated with OC levels, suggesting that females with high lipid metabolism redistributed more OCs from adipose tissue, and that egg production is an important elimination route for OCs. Thirdly, the direct climate effects were assessed using the mean effective temperature (ET: air temperature and wind speed) during incubation, and we hypothesized that a low ET would increase redistribution of OCs. Contrary to expectation, the ET was positively correlated to most OCs, suggesting that a warmer climate may lead to higher OCs levels, and that the impact of ET may not be direct. Finally, potential indirect impacts were examined using the Arctic Oscillation (AO) in the three preceding winters (AOwinter 1–3) as a proxy for potential long-range transport of OCs, and for local spring climate conditions. In addition, we used chlorophyll a (Chla) as a measure of spring primary production. There were negative associations between AOwinter 1 and HCB, trans-chlordane and trans-nonachlor, whereas oxychlordane and cis-chlordane were negatively associated with Chla. This suggests that potential indirect climate effects on eiders were manifested through the food chain and not through increased long-range transport, although these relationships were relatively weak.Impacts of a warming climate on concentrations of organochlorines in a fasting high arctic marine bird: Direct vs. indirect effects?publishedVersio

A Migratory Divide Among Red-Necked Phalaropes in the Western Palearctic Reveals Contrasting Migration and Wintering Movement Strategies

Non-breeding movement strategies of migratory birds may be expected to be flexibly adjusted to the distribution and quality of habitat, but only few studies compare movement strategies between populations using distinct migration routes and wintering areas. In thisour study, individual movement strategies of Rred-necked pPhalaropes Phalaropus lobatus, a long-distance migratory wader using saline waters in the non-breeding period, were studied using light-level geolocators. Results revealed the existence of two populations with distinct migration routes and wintering areas: one breeding in the north-eastern North Atlantic and migrating ca. 10,000 km oversea to the tropical eastern Pacific Ocean and the other breeding in Fennoscandia and Russia migrating ca. 6,000 km – largely over land – to the Arabian Sea (Indian Ocean). In line with our expectations, the transoceanic migration between the North Atlantic and the Pacific was associated with proportionately longer wings, a more even spread of stopovers in autumn and a higher migration speed in spring compared to the migration between Fennoscandian-Russian breeding grounds and the Arabian Sea. In the wintering period, birds wintering in the Pacific were stationaryresided in roughly a singlethe same area, whereas individuals wintering in the Arabian Sea showed individually consistent movementsd extensively between different areas, reflecting differences in spatio-temporal variation in primary productivity between the two wintering areas. Our study is unique in showing how habitat distribution shapes movement strategies over the entire non-breeding period within a species.Peer reviewe

Assessing the Effects of Climate on Host-Parasite Interactions: A Comparative Study of European Birds and Their Parasites

[Background] Climate change potentially has important effects on distribution, abundance, transmission and virulence of parasites in wild populations of animals. [Methodology/Principal Finding] Here we analyzed paired information on 89 parasite populations for 24 species of bird hosts some years ago and again in 2010 with an average interval of 10 years. The parasite taxa included protozoa, feather parasites, diptera, ticks, mites and fleas. We investigated whether change in abundance and prevalence of parasites was related to change in body condition, reproduction and population size of hosts. We conducted analyses based on the entire dataset, but also on a restricted dataset with intervals between study years being 5–15 years. Parasite abundance increased over time when restricting the analyses to datasets with an interval of 5–15 years, with no significant effect of changes in temperature at the time of breeding among study sites. Changes in host body condition and clutch size were related to change in temperature between first and second study year. In addition, changes in clutch size, brood size and body condition of hosts were correlated with change in abundance of parasites. Finally, changes in population size of hosts were not significantly related to changes in abundance of parasites or their prevalence. [Conclusions/Significance] Climate change is associated with a general increase in parasite abundance. Variation in laying date depended on locality and was associated with latitude while body condition of hosts was associated with a change in temperature. Because clutch size, brood size and body condition were associated with change in parasitism, these results suggest that parasites, perhaps mediated through the indirect effects of temperature, may affect fecundity and condition of their hosts. The conclusions were particularly in accordance with predictions when the restricted dataset with intervals of 5–15 years was used, suggesting that short intervals may bias findings.The Academy of Finland is acknowledged for a grant to TE (project 8119367) and EK (project 250709). PLP was supported by a research grant (TE_291/2010) offered by the Romanian Ministry of Education and Science. T. Szép received funding from OTKA K69068 and JT from OTKA 75618. JMP was supported by a JAE grant from Consejo Superior de Investigaciones Científicas. SM-JM, FdL-AM, JF, JJS and FV were respectively supported by projects CGL2009-09439, CGL2012-36665, CGL2009- 11445, CGL2010-19233-C03-01 and CGL2008-00562 by the Spanish Ministry of Science and Innovation and FEDER and project EVITAR by the Spanish Ministry of Health. FV was also supported by the European Regional Development Fund. MACT was funded by a predoctoral FPU grant from the Spanish Ministry of Education (AP20043713). PM was supported by grant from the Polish Ministry of Science and Higher Education (project 2P04F07030), and the Foundation for Polish Science

Krykkje på Melkøya. Sjøfugl i et industrianlegg

Systad, G.H. & Hanssen, S.A. 2016. Krykkje på Melkøya - Sjøfugl i et industrianlegg - NINA Rapport 1227 30 s. I 2004 etablerte flere par krykkje Rissa tridactyla seg på Melkøya, innenfor området til LNG-fabrikken. Nå hekker den i flere fjellskjæringer inne på industrianlegget. Bestanden økte raskt de første årene, og når overvåkningsprosjektet startet i 2011 hekket det mer enn 2000 par i kolo-nien. Fuglebestandene ellers på øya var gått noe tilbake, men det hekket fortsatt en god del gråmåke, svartbak, grågås og ærfugl på øya i 2001. Arter knyttet til kulturlandskapet rundt den opprinnelige bebyggelsen på øya, var forsvunnet. Krykkjekolonien har i de senere år fortsatt å vokse noe, men det virker som at predasjonen i kolonien også har økt. Svartbak, gråmåke og ravn er aktive predatorer i kolonien, og havørn er også blitt vanligere. Bestanden fluktuerer nå rundt 2000 par, og var på topp i 2013, da det hekket ca. 2600 par. Hekkesuksessen til krykkjene på Melkøya har variert mellom 0.98 unger per reir i 2011 og hekkesvikt med 0.06 unger per reir i 2014. Dette sammenfaller nokså godt med utvik-lingen ellers i landsdelen. Flere andre krykkjekolonier i Vest-Finnmark er fulgt og er brukt som sammenligningsgrunnlag for utviklingen i kolonien på Melkøya. I 2011 var hekkesuksessen på Melkøya høyere enn de fleste andre koloniene, unntatt Eidvågen på Seiland, men har etter dette samvariert med disse koloniene. Melkøyakolonien vokste hurtig årene før dette studiet startet, mest sannsynlig som en effekt av immigrasjon fra flere andre kolonier i Vest-Finnmark. Flere av disse er kraftig redusert de siste tiårene, og mange kolonier er forsvunnet helt

Overvåking av hekkende horndykker i Troms 2023

Hanssen, S.A, og Strand Bakke, K.S. 2023 Overvåking av hekkende horndykker i Troms 2023. NINA Rapport 2346. Norsk institutt for naturforskning. NINA har overvåket antallet hekkende/territorielle par horndykker Podiceps auritus på 52 lokaliteter fordelt på åtte kommuner i Troms. Siden oppstarten i 2001 har hekkebestanden blitt redusert med rundt 90 % og den sterkeste nedgangen skjedde fra 2009 til 2010. Etter 2010 stoppet denne tilbakegangen noe opp, og tallet er nå relativt stabilt på et lavt nivå. I 2023 ble 48 av 52 opprinnelige lokaliteter fordelt på åtte kommuner overvåket. Ett av vannene i Bardu kommune, samt lokalitetene i Lyngen kommune, ble ikke overvåket. I tillegg overvåkes én ny lokalitet (fra 2019) på Hinnøya, Sør-Troms. Dermed ble 49 lokaliteter fordelt på åtte kommuner overvåket i 2023 i Troms. Det var et relativt gjennomsnittlig hekkeår for arten med 23 hekkende eller territorielle par innenfor de opprinnelige overvåkingslokalitetene og to territorielle par horndykkere på lokaliteten på Hinnøya. Horndykkerbestanden har ikke kommet seg etter den særdeles dårlige hekkesesongen i 2010. Basert på datasettet for de siste årene er det ikke lenger noe usikkerhet omkring bestandsutviklingen hos horndykker. Horndykkeren sliter med en kraftig bestandsnedgang i mange av overvåkingsvannene. I 2023 var antallet horndykkerpar i de opprinnelige overvåkingslokalitetene kun 10.1 % av hekkebestanden i 2001. Det anbefales at overvåkingen utvides til å omfatte flere områder i Sør-Troms og da spesielt på Senja og Hinnøya. Dette vil gi økt kunnskap om den delen av hekkebestanden som ligger nær kysten av Sør-Troms. I 2018-2022 ble til sammen 9 horndykkere instrumentert med lysloggere, det vil kunne avdekke trekkruter og overvintringsområder for denne truede arten. Slike lysloggerstudier er avhengig av et langt tidsperspektiv da fuglene med loggere må fanges inn før data kan avleses. Flere fugler må instrumenteres over tid for å få et bredt nok datamateriale som kan fange opp variasjoner i trekktidspunkter og vinterområder mellom individer og sesonger. Dette vil kunne gi viktige data for forvaltningen i forhold til vern av horndykker også utenfor hekkeområdene. Denne delen av prosjektet ble delfinansiert av Miljødirektoratet i 2023. Dessverre lyktes ikke fangsten i 2023 og ingen horndykkere ble instrumentert i 2023.Hanssen, S.A, og Strand Bakke, K.S. 2023. Monitoring of breeding Slavonian grebes in Troms 2023. NINA Report 2346. Norwegian Institute for Nature Research. NINA has monitored the number of breeding/territorial pairs of the Slavonian grebe (Podiceps auritus) at 52 sites across eight municipalities in Troms. Since the start of the monitoring programme in 2001, the breeding population has been reduced by approximately 90%, with the most significant decline occurring from 2009 to 2010. After 2010, this decline somewhat stabilized, and the numbers are now relatively stable at a low level. In 2023, 48 out of the original 52 sites across eight municipalities were monitored. One of the lakes in Bardu municipality and the sites in Lyngen municipality were not monitored. Additionally, one new site (from 2019) on Hinnøya, South Troms, was monitored. Thus, 49 sites across eight municipalities were monitored in 2023 in Troms. It was a relatively average breeding year for the species, with 23 breeding or territorial pairs within the original monitoring sites and two territorial pairs of Slavonian grebes at the Hinnøya site. The Slavonian grebe population has not recovered from the exceptionally poor breeding season in 2010. Based on the dataset from recent years, there is no longer any uncertainty about the population trend of the Slavonian grebe. The Slavonian grebe is struggling with a significant population decline in many of the monitored lakes. In 2023, the number of Slavonian grebe pairs in the original monitoring sites was only 10.1% of the breeding population in 2001. It is recommended to expand the monitoring to include more areas in South Troms, especially on Senja and Hinnøya. This will provide increased knowledge about the part of the breeding population that is close to the coast of South Troms. From 2018 to 2022, a total of 9 Slavonian grebes were instrumented with light loggers to uncover migration routes and wintering areas for this endangered species. Such light logger studies depend on a long-term perspective because the birds with loggers must be recaptured before data can be read. Several birds must be instrumented over time to gather a broad enough dataset that can capture variations in migration timings and wintering areas between individuals and seasons. This will provide important data for conservation efforts related to the protection of the Slavonian grebe, even outside of their breeding areas. The logger part of the project was partially funded by the Norwegian Environment Agency in 2023. Unfortunately, no birds were successfully captured in 2023, and no Slavonian grebes were instrumented that year

Overvåking av hekkende horndykker i Troms 2022

Hanssen, S.A, og Strand Bakke, K.S. 2022 Overvåking av hekkende horndykker i Troms 2022. NINA Rapport 2194. Norsk institutt for naturforskning. NINA har overvåket antallet hekkende/territorielle par horndykker Podiceps auritus på 52 lokaliteter fordelt på åtte kommuner i Troms. Siden oppstarten i 2001 har hekkebestanden blitt redusert med rundt 90 % og den sterkeste nedgangen skjedde fra 2009 til 2010. Etter 2010 stoppet denne tilbakegangen noe opp, og tallet er nå relativt stabilt på et lavt nivå. I 2022 ble 48 av 52 opprinnelige lokaliteter fordelt på åtte kommuner overvåket. Ett av vannene i Bardu kommune, samt lokalitetene i Lyngen kommune, ble ikke overvåket. I tillegg overvåkes én ny lokalitet (fra 2019) på Hinnøya, Sør-Troms. Dermed ble 49 lokaliteter fordelt på åtte kommuner overvåket i 2022 i Troms. Det var et relativt gjennomsnittlig hekkeår for arten med 22 hekkende eller territorielle par innenfor de opprinnelige overvåkingslokalitetene og to territorielle par horndykkere på lokaliteten på Hinnøya. Horndykkerbestanden har ikke kommet seg etter den særdeles dårlige hekkesesongen i 2010. Basert på datasettet for de siste årene er det ikke lenger noe usikkerhet omkring bestandsutviklingen hos horndykker. Horndykkeren sliter med en kraftig bestandsnedgang i mange av overvåkingsvannene. I 2022 er antallet horndykkerpar i de opprinnelige overvåkingslokalitetene kun 9.6 % av hekkebestanden i 2001. Det anbefales at overvåkingen utvides til å omfatte flere områder i Sør-Troms og da spesielt på Senja og Hinnøya. Dette vil gi økt kunnskap om den delen av hekkebestanden som ligger nær kysten av Sør-Troms. I 2018-2021 ble til sammen 8 horndykkere instrumentert med lysloggere, det vil kunne avdekke trekkruter og overvintringsområder for denne truede arten. Slike lysloggerstudier er avhengig av et langt tidsperspektiv da fuglene med loggere må fanges inn før data kan avleses. Flere fugler må instrumenteres over tid for å få et bredt nok datamateriale som kan fange opp variasjoner i trekktidspunkter og vinterområder mellom individer og sesonger. Dette vil kunne gi viktige data for forvaltningen i forhold til vern av horndykker også utenfor hekkeområdene. Loggerdelen av prosjektet ble ikke finansiert av Statsforvalteren i Troms og Finnmark i 2022. Imidlertid ble det ved bruk av betydelig egeninnsats fanget inn og instrumentert 1 ny horndykker i 2022.Hanssen, S.A, og Strand Bakke, K.S. 2022. Monitoring of breeding Slavonian grebes in Troms 2022. NINA Report 2194. Norwegian Institute for Nature Research. The number of breeding Slavonian grebes Podiceps auritus has since 2001 been monitored in 52 sites in Troms County in Northern Norway. The breeding population has been reduced by 90% since the start of the monitoring programme, with the strongest decline between 2009 and 2010. After 2010 this decline has levelled off and the population is now relatively stable but low. In 2022, 48 of the 52 originally monitored sites were monitored. With a total of 22 breeding or territorial pairs within the 49 original monitored sites in Troms and 2 breeding pairs at Hinnøya, the breeding season 2022 was relatively poor. The Slavonian grebe population has not recovered after the unsuccessful breeding season in 2010. Based on the data for the more recent years there is no longer any uncertainty regarding the population decline of the Slavonian grebe. In 2022 the population numbers are 9.6% of the 2001 level. We recommend that the monitoring area should be expanded to more sites in the southern part of Troms, especially on the islands Senja and Hinnøya. This will increase the knowledge of the coastal breeding population of Slavonian grebes. In 2018 - 2021 eight grebes were instrumented with light loggers (gls-loggers) to uncover the migration routes and wintering areas of this population. These logger studies depend on a longer time frame as birds will have to be recaptured to obtain that data from the loggers. More birds will have to be instrumented during the next years to uncover the variation in migration routes and wintering areas, both on a population an individual level. This will provide important knowledge for the management of this species, both within and outside of the breeding areas. The logger project did not receive any funding from the County Governor of Troms and Finnmark in 2022. However, with the help of substantial voluntary effort one grebe was caught and instrumented in 2022