Consequences of cross‐season demographic correlations for population viability

Demographic correlations are pervasive in wildlife populations and can represent important secondary drivers of population growth. Empirical evidence suggests that correlations are in general positive for long-lived species, but little is known about the degree of variation among spatially segregated populations of the same species in relation to environmental conditions. We assessed the relative importance of two cross-season correlations in survival and productivity, for three Atlantic puffin (Fratercula arctica) populations with contrasting population trajectories and non-overlapping year-round distributions. The two correlations reflected either a relationship between adult survival prior to breeding on productivity, or a relationship between productivity and adult survival the subsequent year. Demographic rates and their correlations were estimated with an integrated population model, and their respective contributions to variation in population growth were calculated using a transient-life table response experiment. For all three populations, demographic correlations were positive at both time lags, although their strength differed. Given the different year-round distributions of these populations, this variation in the strength population-level demographic correlations points to environmental conditions as an important driver of demographic variation through life-history constraints. Consequently, the contributions of variances and correlations in demographic rates to population growth rates differed among puffin populations, which has implications for—particularly small—populations' viability under environmental change as positive correlations tend to reduce the stochastic population growth rate

Raising offspring increases ageing: differences in senescence among three populations of a long‐lived seabird, the Atlantic puffin

1. Actuarial senescence, the decline of survival with age, is well documented in the wild. Rates of senescence vary widely between taxa, to some extent also between sexes, with the fastest life histories showing the highest rates of senescence. Few studies have investigated differences in senescence among populations of the same species, although such variation is expected from population-level differences in environmental conditions, leading to differences in vital rates and thus life histories. 2. We predict that, within species, populations differing in productivity (suggesting different paces of life) should experience different rates of senescence, but with little or no sexual difference in senescence within populations of monogamous, monomorphic species where the sexes share breeding duties. 3. We compared rates of actuarial senescence among three contrasting populations of the Atlantic puffin Fratercula arctica. The dataset comprised 31 years (1990–2020) of parallel capture–mark–recapture data from three breeding colonies, Isle of May (North Sea), Røst (Norwegian Sea) and Hornøya (Barents Sea), showing contrasting productivities (i.e. annual breeding success) and population trends. We used time elapsed since first capture as a proxy for bird age, and productivity and the winter North Atlantic Oscillation Index (wNAO) as proxies for the environmental conditions experienced by the populations within and outside the breeding season, respectively. 4. In accordance with our predictions, we found that senescence rates differed among the study populations, with no evidence for sexual differences. There was no evidence for an effect of wNAO, but the population with the lowest productivity, Røst, showed the lowest rate of senescence. As a consequence, the negative effect of senescence on the population growth rate (λ) was up to 3–5 times smaller on Røst (Δλ = −0.009) than on the two other colonies. 5. Our findings suggest that environmentally induced differences in senescence rates among populations of a species should be accounted for when predicting effects of climate variation and change on species persistence. There is thus a need for more detailed information on how both actuarial and reproductive senescence influence vital rates of populations of the same species, calling for large-scale comparative studies

Earlier colony arrival but no trend in hatching timing in two congeneric seabirds (Uria spp.) across the North Atlantic

A global analysis recently showed that seabird breeding phenology (as the timing of egg-laying and hatching) does not, on average, respond to temperature changes or advance with time (Keogan et al. 2018 Nat. Clim. Change8, 313–318). This group, the most threatened of all birds, is therefore prone to spatio-temporal mismatches with their food resources. Yet, other aspects of the breeding phenology may also have a marked influence on breeding success, such as the arrival date of adults at the breeding site following winter migration. Here, we used a large tracking dataset of two congeneric seabirds breeding in 14 colonies across 18° latitudes, to show that arrival date at the colony was highly variable between colonies and species (ranging 80 days) and advanced 1.4 days/year while timing of egg-laying remained unchanged, resulting in an increasing pre-laying duration between 2009 and 2018. Thus, we demonstrate that potentially not all components of seabird breeding phenology are insensitive to changing environmental conditions

The decline of Norwegian kittiwake populations: modelling the role of ocean warming.

The black-legged kittiwake Rissa tridactyla is a pelagic seabird whose population has recently declined in most parts of the North Atlantic and which is red-listed in most bordering countries. To investigate a possible cause for this decline, we analysed the population dynamics of 5 kittiwake colonies along the Norwegian coast, ranging from 62° to 71° N, over the last 20 to 35 yr. By quantifying the importance of sea surface temperatures (SST) in relevant areas of the North Atlantic, we tested the importance of climatic conditions throughout the populations’ annual cycles. We found no synchrony among colonies; however, SST affected population dynamics, explaining between 6% and 37% (average 18%) of the variation in annual population growth rate. While dynamics of the southerly colonies were mainly affected by winter conditions in the Grand Banks area, dynamics of the northernmost colonies were dominated by autumn conditions off Svalbard. Negative slopes indicated stronger population decline under warmer ocean conditions. Population dynamics were affected both via adult survival and offspring recruitment, as evidenced by the presence of unlagged effects as well as effects lagged by the age at recruitment. Finally, we performed population viability analyses taking into account the projected warming trends for the future. The median time to extinction of the Norwegian colonies was 52 to 181 yr without considering covariates; 45 to 94 yr when considering the effects of SST but ignoring future warming; and 10 to 48 yr when ocean warming, based on a ‘business as usual’ scenario, was taken into account. Global warming · Non-breeding distribution · Population dynamics · Population viability analysis · Rissa tridactyla · Sea surface temperatur

Development of a Cumulative Impact Assessment tool for birds in Norwegian Offshore Waters: Trollvind OWF as a case study

Layton-Matthews K., Buckingham L., Critchley E.J., Nilsson A.L.K., Ollus VMS., Ballesteros M., Christensen-Dalsgaard S., Dehnhard N., Fauchald P., Hanssen F., Helberg M., Masden E., May R.F., Sandvik H., Tarroux A. & Reiertsen T.K. 2023. Development of a Cumulative Impact Assessment tool for birds in Norwegian Offshore Waters: Trollvind OWF as a case study. NINA Report 2295. Norwegian Institute for Nature Research. There is growing interest in the economic potential of marine areas for e.g., offshore renewables, fisheries, and shipping. Thus, the cumulative stress on marine ecosystems and the species inhabiting them is increasing. This is of particular concern for migratory birds and seabirds which are undergoing global declines. In the light of an expanding global market for offshore renewables, knowledge of their cumulative impacts combined with other human-derived pressures on marine populations is crucial. This is set against the backdrop of climate change and associated large-scale changes in our oceans. Achieving sustainable development, while mitigating the effects of climate change, requires effective tools to assess the cumulative impacts of anthropogenic stressors on ecosystems. Cumulative impact assessments for the marine environment are strongly influenced by an approach developed by Halpern et al. (2008). In this report, we present and demonstrate a beta-version of a cumulative impact assessment tool for marine industrial pressures on seabirds, which is being developed through the Research Council of Norway (RCN) -funded MARCIS project. The goal of MARCIS is to assess the impacts of marine anthropogenic pressures on seabirds in the North-East Atlantic, which will both utilise and further develop the Halpern formula and provide a publicly open web-based tool that acts as a decision support for marine spatial planning. Equinor has been exploring the potential for con-structing a floating offshore wind farm, called Trollvind, in the North Sea. This proposed floating wind farm is in the early planning stages of development and is proposed to be located around the Troll offshore oil and gas platforms, approximately 65 km west of Bergen. This report presents; 1) a summary of a scoping of existing data of birds using Norwegian offshore area, 2) an assessment of bird migration through the North Sea and the Trollvind area, and the likelihood that some bird groups will be more impacted by an offshore wind farm in this area, and 3) a demonstration of the tool under development (the MARCIS web application), where we assess the potential cumulative impact of the proposed Trollvind OWF development and ocean warming on two seabird populations, as a case study. This report has specific emphasis on the demonstration of the tool. Results of the scoping study of birds using the Norwegian offshore areas indicated a below-medium to medium sensitivity of waterbirds to wind farms in the Trollvind area. However, there were strong seasonal differences showing above-medium values in summer in the eastern and north-eastern parts of the area. Our results also revealed that migratory bird groups differ in their type of risks of impact associated with the Trollvind development, where migrating raptors, gulls, waterfowl and owls were at greatest risk of collision, while migrating seabirds, waterbirds and waders had a higher risk of displacement and/or barrier effects. In the demo of the tool, we estimated the cumulative impact of two stressors (Trollvind OWF and ocean warming) on two study populations (kittiwake breeding at Ålesund colony and common guillemot from Sklinna colony). Both their non-breeding distribution and the cumulative impact of the two stressors was visualised in the demo of the MARCIS App. The impact of Trollvind OWF was negligible for both populations, while disturbance led to a small reduction in guillemots’ body mass and consequently their survival rates. However, ocean warming had a larger population impact, given the high emissions scenario used to quantify impact weights, particularly for guillemots. However, it is important to keep in mind that this demonstration is a case study of only two populations and should be interpreted in the larger context of the results from the scoping study and bird migration studies. The extensive range of species using this area at different times of year are much larger, and this has implementations for a potentially broader impact of such offshore developments. This also highlights the need for both spatial explicit distribution data and demographic/population data to ensure an appropriate knowledge base of population impacts before any OWF developments are conducted.Layton-Matthews K., Buckingham L., Critchley E.J., Nilsson A.L.K., Ollus V.M.S., Ballesteros M., Christensen-Dalsgaard, S., Dehnhard N., Fauchald P., Hanssen F., Helberg M., Masden E., May R.F., Sandvik H., Tarroux A. & Reiertsen T.K. 2023. Development of a Cumulative Impact As-sessment tool for birds in Norwegian Off-shore Waters: Trollvind OWF as a case study. NINA Rapport 2295. Norsk institutt for naturforskning. Presset på marine områder øker med økende økonomiske interesser for bruk av havområdene. Marine områder har blitt viktige arenaer for industriell utvikling som for eksempel havvind, petroleumsaktivitet, skipstrafikk og fiskeri. I lys av et ekspanderende globalt marked for havvind, er kunnskap om sumeffekter av både havvind, andre marine industriaktiviteter og klimaendringer avgjørende for å sikre en god sameksistens med sjøfugl og trekkfugler som benytter de samme havområdene. Økt utnyttelse av havarealene øker sumeffektene og stresset på marine økosystemer og artene som bor der, sett i lys av klima- og økosystem-endringene som skjer i marine økosystemer. Å oppnå bærekraftig utvikling, samtidig som effektene av klimaendringer reduseres, krever effektive verktøy for å vurdere sumeffektene av menneskeskapte stressfaktorer på økosystemene. Metoder for å estimere sumeffekter for havmiljøet er sterkt påvirket av en tilnærming utviklet av Halpern et al. (2008), som ser på summen av ulike stressfaktorer sin påvirkning på et miljø og miljøets sensitivitet til de ulike stressfaktorene. I denne rapporten vil vi presentere og demonstrere en betaversjon av et verktøy som kan benyttes i marin arealplanlegging og som kvantifiserer effekter av marin industri aktivitet på sjøfugler. Dette verktøyet utvikles gjennom det forskningsråds-finansierte MARCIS-prosjektet. Målet med MARCIS er å vurdere virkningene av marin industriaktivitet og klimaendringer på sjøfugler i Nordøst-Atlanteren, og vil både benytte og videreutvikle Halpern-metoden. Verktøyet vil bli gjort tilgjengelig som et offentlig åpent nettbasert verktøy, og kan fungere som beslutningsstøtte for marin arealplanlegging. Equinor har undersøkt potensialet for bygging av en flytende havvindpark, kalt Trollvind, i Nordsjøen. Denne flytende vindparken er i et tidlig planleggingsstadium og foreslås plassert rundt olje- og gassplattformene i Trollfeltet, ca. 65 km vest for Bergen. Denne rapporten presenterer: 1)en oppsummering av en scoping av eksisterende data om fugler som bruker i norsk offshore-område, 2) en vurdering av fugletrekk gjennom Nordsjøen og Trollvind-området, og sannsynligheten for at noen fuglegrupper blir mer påvirket av en havvindpark i dette området, og 3) endemonstrasjon av verktøyet som er under utvikling (MARCIS-webapplikasjonen), der vi vurdererde potensielle sumeffektene av den foreslåtte Trollvind OWF-utbyggingen og havoppvarmingenpå to sjøfuglbestander, som et casestudie. Denne rapporten har lagt spesifikk vekt på demon-strasjonen av verktøyet. Resultatene av dette studiet indikerte at trekkfugler knyttet til vann (eks. dykkere, lom osv) hadde en under middels til middels følsomhet for havvindparker i Trollvind-området. Det var imidlertid sterke sesongforskjeller som viste over middels verdier om sommeren i østlige og nordøstlige deler av området. Resultatene våre avdekket også at grupper av trekkfugl hadde ulik risiko for å bli påvirket av en havvind-utbygging knyttet Trollvind-området. Trekkende rovfugler, måker, gjess og ender, og ugler hadde størst risiko for kollisjon med turbiner, mens trekkende sjøfugler, andre fugler knyttet til vann og vadefugler hadde høyere risiko for å bli fordrevet fra området eller utsatt for barriereeffekter av havvind-installasjoner. Sum-effektene av to ulike stressfaktorer (Trollvind havvindpark og havoppvarming) ble estimert for to studiepopulasjoner (krykkje og lomvi fra hhv Ålesund og Sklinna) og visualisert i betaversjonen av MARCIS-appen. Effekten av en potensiell havvind-installasjon i Trollvind området var ubetydelig for begge popu-lasjoner, mens fordrivelse fra området førte til en liten reduksjon i lomviens kroppsmasse og dermed effekt på bestandens overlevelsesrate. Havoppvarmingen hadde imidlertid en større påvirkning på bestandene, og spesielt for lomvi. Det er imidlertid viktig å huske på at denne demonstrasjonen er en casestudie av bare to populasjoner og bør tolkes i en større kontekst i lys av resultatene fra scoping-studiet og fugletrekkstudiet. Begge disse viser det omfattende spekteret av arter som bruker dette området, og hvordan mengde og sammensetning av arter varierer til ulike tider av året. Effekten av en offshore havvind utbygging i Trollvind området har dermed en potensielt større effekt. Dette fremhever også behovet for gode data, både romlige distribusjonsdata og data på demografiske rater eller bestandstall for å sikre et godt nok kunnskapsgrunnlag om effekter på populasjoner før eventuelle havvind-utbygginger tar til

Cod larvae abundances

Abundances and weights of cod larvae from different spawning grounds around the guillemot colony at Hornøya, by date and yea

Guillemot measurements

Biometry, phenology and CORT measurements of adult and juvenile common guillemots on Hornøy

Prey density in non-breeding areas affects adult survival of Black-legged Kittiwakes Rissa tridactyla

In migratory birds, environmental conditions in both breeding and non-breeding areas may affect adult survival rates and hence be significant drivers of demographic processes. In seabirds, poor knowledge of their true distribution outside the breeding season, however, has severely limited such studies. This study explored how annual adult survival rates of black-legged kittiwakes Rissa tridactyla on Hornøya in the southern Barents Sea were related to temporal variation in prey densities and climatic parameters in their breeding and non-breeding areas. We used information on the kittiwakes" spatiotemporal distribution in the non-breeding season gained from year-round light-based tracking devices (geolocators) and satellite transmitters, and kittiwake annual adult survival rates gained from a multistate capture-mark-recapture analysis of a 22 yr time series of colour-ringed kittiwakes. In the post-breeding period, kittiwakes concentrated in an area east of Svalbard, in the winter they stayed in the Grand Banks/Labrador Sea area, and in the pre-breeding period they returned to the Barents Sea. We identified 2 possible prey categories of importance for the survival of kittiwakes in these areas (sea butterflies Thecosomata in the Grand Banks/Labrador Sea area in winter and capelin Mallotus villosus in the Barents Sea in the pre-breeding season) that together explained 52% of the variation in adult survival rates. Our results may have important implications for the conservation of kittiwakes, which are declining globally, because other populations use the same areas. Since they are under the influence of major anthropogenic activities including fisheries, international shipping and the offshore oil and gas industry, both areas should be targeted for future management plans

Individual migration strategy fidelity but no habitat specialization in two congeneric seabirds

Aim: In migratory species, individuals often use fixed and individual‐specific migration strategies, which we term individual migration strategy fidelity (IMSF). Our goal was to test if guillemots have flexible or fixed individual migration strategies (i.e. IMSF), if this behaviour is consistent across large parts of the genus’ range and if they were philopatric to geographical sites or a habitat feature. Location: North Atlantic. Taxon: Uria spp. Methods: We quantified consistent individual differences in inter‐annual spatial distribution and habitat occupied throughout the non‐breeding period using a large geolocator tracking dataset of 729 adult seabirds breeding at 13 colonies across the Northeast Atlantic and repeatedly tracked up to 7 years over a 9‐year period. Additionally, we used a similarity index to calculate relative fidelity to either geographical sites or habitats and linear mixed‐effects models to assess persistence of spatial site fidelity over multiple years. Results: Both guillemot species exhibited IMSF across a large part of the genus’ range which persisted over multiple years. Individuals of both species and almost all colonies showed fidelity to geographical sites and not to specific habitats. Main conclusions: Guillemots show IMSF that is best explained by site familiarity (fidelity to specific sites) rather than habitat specialization (fidelity to specific habitats). In the context of rapidly changing environments, favourable habitats may permanently shift locations and hence species displaying IMSF driven by site familiarity—such as the genus Uria—may not be able to adjust their migration strategies sufficiently fast to sustain individual fitness and ensure population persistence

Ocean-wide drivers of migration strategies and their influence on population breeding performance in a declining seabird

Which factors shape animals’ migration movements across large geographical scales, how different migratory strategies emerge between populations, and how these may affect population dynamics are central questions in the field of animal migration [1] that only large-scale studies of migration patterns across a species’ range can answer [2]. To address these questions, we track the migration of 270 Atlantic puffins Fratercula arctica, a red-listed, declining seabird, across their entire breeding range. We investigate the role of demographic, geographical, and environmental variables in driving spatial and behavioral differences on an ocean-basin scale by measuring puffins’ among-colony differences in migratory routes and day-to-day behavior (estimated with individual daily activity budgets and energy expenditure). We show that competition and local winter resource availability are important drivers of migratory movements, with birds from larger colonies or with poorer local winter conditions migrating further and visiting less-productive waters; this in turn led to differences in flight activity and energy expenditure. Other behavioral differences emerge with latitude, with foraging effort and energy expenditure increasing when birds winter further north in colder waters. Importantly, these ocean-wide migration patterns can ultimately be linked with breeding performance: colony productivity is negatively associated with wintering latitude, population size, and migration distance, which demonstrates the cost of competition and migration on future breeding and the link between non-breeding and breeding periods. Our results help us to understand the drivers of animal migration and have important implications for population dynamics and the conservation of migratory species