HPAIV outbreak triggers short-term colony connectivity in a seabird metapopulation

Disease outbreaks can drastically disturb the environment of surviving animals, but the behavioural, ecological, and epidemiological consequences of disease-driven disturbance are poorly understood. Here, we show that an outbreak of High Pathogenicity Avian Influenza Virus (HPAIV) coincided with unprecedented short-term behavioural changes in Northern gannets (Morus bassanus). Breeding gannets show characteristically strong fidelity to their nest sites and foraging areas (2015–2019; n = 120), but during the 2022 HPAIV outbreak, GPS-tagged gannets instigated long-distance movements beyond well-documented previous ranges and the first ever recorded visits of GPS-tagged adults to other gannet breeding colonies. Our findings suggest that the HPAIV outbreak triggered changes in space use patterns of exposed individuals that amplified the epidemiological connectivity among colonies and may generate super-spreader events that accelerate disease transmission across the metapopulation. Such self-propagating transmission from and towards high density animal aggregations may explain the unexpectedly rapid pan-European spread of HPAIV in the gannet

Minimal overlap between areas of high conservation priority for endangered Galapagos pinnipeds and the conservation zone of the Galapagos Marine Reserve

Galapagos sea lions (Zalophus wollebaeki) and fur seals (Arctocephalus galapagoensis) are endangered pinnipeds that live in a highly variable marine environment, influenced by seasonal changes in productivity and by the unpredictable occurrence of El Niño. The Galapagos marine habitat is protected through the Galapagos Marine Reserve (GMR), which has recently undergone a redefinition of its zonation. However, the effectiveness of the GMR in protecting the habitat of Galapagos pinnipeds has never been investigated, and it is unclear how well their habitat use aligns with the newly proposed conservation zone. A spatial prioritization analysis framework was applied based on the complementary use of density estimation (kernel utilization distributions, KUDs) and habitat modelling (resource selection functions, RSFs). Using tracking data collected over two years and under three environmental scenarios (cold season, warm season, and El Niño) in the western archipelago, hot spots of pinniped habitat usage were identified (through KUDs), and predictions about the location of patches of good habitat were generated (through RSFs). The output of KUDs and RSFs was used for a spatial prioritization analysis to delineate areas of high conservation priority. The overlap between these areas and the GMR zonation was then calculated. Both species were found to use largely distinct habitat types: sea lions used the waters over the continental shelf, whereas fur seals used the offshore deep waters and showed a more heterogeneous space usage over time. The spatial prioritization analysis identified three key areas of high conservation priority for both species in the Western Galapagos. These areas were all within the boundaries of the GMR but the overlap with the conservation zone was only 8%. Hence, under the current proposition, the largest proportion of key pinniped foraging habitat in the western archipelago will not be protected from licensed activities in the sustainable use zone, particularly fishing and boat traffic

The Galapagos sea lion: adaptation to spatial and temporal diversity of marine resources within the archipelago

Galapagos sea lions are the smallest sea lion species worldwide. The population consists of about 20,000 individuals, is endemic to the Galapagos Islands and has been separated for about 2.5 million years from the California sea lion. The equatorial environment differs from that of other pinnipeds by terrestrial heat and reduced marine productivity. Growth and development is strongly influenced by marine variability, particularly El Niño events, which also decrease juvenile and adult survival. Large males establish aquatic territories, but smaller non-territorial males also achieve reproductive success. Time at the colony proves the best predictor of reproductive success, which reflects the long drawn-out reproductive season often lasting 6 months. Females mature relatively late at about 5 years and reproduce often only every other year. Juveniles need exceptionally long to become nutritionally independent. The long period of lactation (2–5 years) often leads to competition between offspring born in different years. Adult females dive to great depths (max. 580 m) and mostly forage on shelf areas as well as along the shelf edge. Juveniles need many years to reach adult diving abilities. Increased human-sea lion contact in fast growing settlements and through boat traffic and fishery poses new and potentially highly dangerous threats to the population

Differences in foraging ecology align with genetically divergent ecotypes of a highly mobile marine top predator

Foraging differentiation within a species can contribute to restricted gene flow between ecologically different groups, promoting ecological speciation. Galapagos sea lions (Zalophus wollebaeki) show genetic and morphological divergence between the western and central archipelago, possibly as a result of an ecologically mediated contrast in the marine habitat. We use global positioning system (GPS) data, time-depth recordings (TDR), stable isotope and scat data to compare foraging habitat characteristics, diving behaviour and diet composition of Galapagos sea lions from a western and a central colony. We consider both juvenile and adult life stages to assess the potential role of ontogenetic shifts that can be crucial in shaping foraging behaviour and habitat choice for life. We found differences in foraging habitat use, foraging style and diet composition that aligned with genetic differentiation. These differences were consistent between juvenile and adult sea lions from the same colony, overriding age-specific behavioural differences. Our study contributes to an understanding of the complex interaction of ecological condition, plastic behavioural response and genetic make-up of interconnected populations

The influence of weather and tides on the land basking behavior of Green Sea turtles (Chelonia mydas) in the Galapagos Islands

We monitored green sea turtle (Chelonia mydas) land basking behavior on Fernandina Island in the Galapagos Islands to determine the potential influence of tide level and weather on the presence and abundance of turtles. Using generalized linear models, we found that both presence and abundance of turtles were related to lower tide levels but that abundance was further related to higher air temperatures, reduced cloud cover, and falling tides; additionally, we recorded more males than have been found in other studies (males  =  41.5% of observations). We hypothesize that haul out during low tide reduces energy expenditure of activities such as coming to the surface to breathe; however, more turtles take advantage of this behavior when conditions such as air temperature and cloud cover are more conducive to physiological benefits such as thermoregulation or acceleration of digestion

Effects of age and reproductive status on individual foraging site fidelity in a long-lived marine predator

This work was funded by the Natural Environment Research Council (Standard grant no. NE/H007466/1; New Investigators grant no. NE/H007466/1) and a German Academic Exchange Service (DAAD) Postdoctoral Fellowship and a Leadership Fellowship by the University of Glasgow to J.W.E.J. Data are available via Dryad (http://dx.doi.org/10.5061/dryad.8m1nf)Individual foraging specializations, where individuals use a small component of the population niche width, are widespread in nature with important ecological and evolutionary implications. In long-lived animals, foraging ability develops with age, but we know little about the ontogeny of individuality in foraging. Here we use precision global positioning system (GPS) loggers to examine how individual foraging site fidelity (IFSF), a common component of foraging specialization, varies between breeders, failed breeders and immatures in a long-lived marine predator— the northern gannet Morus bassanus. Breeders (aged 5+) showed strong IFSF: they had similar routes and were faithful to distal points during successive trips. However, centrally placed immatures (aged 2–3) were far more exploratory and lacked route or foraging site fidelity. Failed breeders were intermediate: some with strong fidelity, others being more exploratory. Individual foraging specializations were previously thought to arise as a function of heritable phenotypic differences or via social transmission. Our results instead suggest a third alternative—in long-lived species foraging sites are learned during exploratory behaviours early in life, which become canalized with age and experience, and refined where possible— the exploration-refinement foraging hypothesis. We speculate similar patterns may be present in other long-lived species and moreover that long periods of immaturity may be a consequence of such memory-based individual foraging strategies.Publisher PDFPeer reviewe

Integrated modelling of seabird-habitat associations from multi-platform data: a review

Quantifying current and future overlap between human activities and wildlife is a core and growing aim of ecological study, spurring ever more spatial data collection and diversification of observation techniques (surveys, telemetry, citizen science etc.). To meet this aim, data collected via multiple platforms, across different geographical and temporal regions, may need to be integrated, yet many ecologists remain unclear about the relationships between data types and therefore how they can be combined. In seabird research, these applied questions can be particularly pressing because many human activities (e.g. tidal and wind renewables, fishing, shipping, etc.) are concentrated in coastal waters, where many seabirds also aggregate, especially while breeding. In addition, seabird coloniality and density dependence present unique analytical challenges. We review the relevant literature on data integration and illustrate it with example models and data (in an accompanying R-library and vignette (J Matthiopoulos et al., 2022)), to derive methodological and quantitative guidelines for best practice in conducting joint inference for multi-platform data. We use systematic survey data to motivate the key arguments, but also overview developments in integration with other data (e.g., telemetry tracking, citizen science, mark-recapture). We make recommendations on (1) the use of response and explanatory data, (2) the treatment of survey design and observation errors, (3) exploiting dependencies across space and time, (4) accounting for biological phenomena, such as commuting costs from the colony (i.e., accessibility) and density dependence, and (5) the choice of statistical framework. Synthesis and application: Integrated analysis of multi-platform data turns many of the seabird-specific challenges into opportunities for inferring habitat associations and predicting future distributions. Our review proposes practical recommendations for data collection and analysis that will allow seabird conservation to derive maximal benefits from these opportunities

Metapopulation regulation acts at multiple spatial scales: Insights from a century of seabird colony census data

Density-dependent feedback is recognized as important regulatory mechanisms of population size. Considering the spatial scales over which such feedback operates has advanced our theoretical understanding of metapopulation dynamics. Yet, metapopulation models are rarely fit to time-series data and tend to omit details of the natural history and behavior of long-lived, highly mobile species such as colonial mammals and birds. Seabird metapopulations consist of breeding colonies that are connected across large spatial scales, within a heterogeneous marine environment that is increasingly affected by anthropogenic disturbance. Currently, we know little about the strength and spatial scale of density-dependent regulation and connectivity between colonies. Thus, many important seabird conservation and management decisions rely on outdated assumptions of closed populations that lack density-dependent regulation. We investigated metapopulation dynamics and connectivity in an exemplar seabird species, the Northern gannet (Morus bassanus), using more than a century of census data of breeding colonies distributed across the Northeast Atlantic. We developed and fitted these data to a novel hierarchical Bayesian state-space model, to compare increasingly complex scenarios of metapopulation regulation through lagged, local, regional, and global density dependence, as well as different mechanisms for immigration. Models with conspecific attraction fit the data better than the equipartitioning of immigrants. Considering local and regional density dependence jointly improved model fit slightly, but importantly, future colony size projections based on different mechanistic regulatory scenarios varied widely: a model with local and regional dynamics estimated a lower metapopulation capacity (645,655 Apparently Occupied Site [AOS]) and consequently higher present saturation (63%) than a model with local density dependence (1,367,352 AOS, 34%). Our findings suggest that metapopulation regulation in the gannet is more complex than traditionally assumed, and highlight the importance of using models that consider colony connectivity and regional dynamics for conservation management applications guided by precautionary principles. Our study advances our understanding of metapopulation dynamics in long-lived colonial species and our approach provides a template for the development of metapopulation models for colonially living birds and mammals

Metapopulation regulation acts at multiple spatial scales: insights from a century of seabird colony census data

Density dependent feedbacks are recognised as important regulatory mechanisms of population size. Considering the spatial scales over which such feedbacks operate has advanced our theoretical understanding of metapopulation dynamics. Yet, metapopulation models are rarely fit to time series data and tend to omit details of the natural history and behaviour of long-lived, highly mobile species such as colonial mammals and birds. Seabird metapopulations consist of breeding colonies that are connected across large spatial scales, within a heterogeneous marine environment that is increasingly affected by anthropogenic disturbance. Currently, we know little about the strength and spatial scale of density dependent regulation and connectivity between colonies. Thus, many important seabird conservation and management decisions rely on outdated assumptions of closed populations that lack density dependent regulation. We investigated metapopulation dynamics and connectivity in an exemplar seabird species, the Northern gannet (Morus bassanus), using more than a century of census data of breeding colonies distributed across the Northeast Atlantic. We developed and fit to these data a novel hierarchical Bayesian state-space model, to compare increasingly complex scenarios of metapopulation regulation through lagged, local, regional, and global density dependence, as well as different mechanisms for immigration. Models with conspecific attraction fit the data better than equipartitioning of immigrants. Considering local and regional density dependence jointly improved model fit slightly, but importantly, future colony size projections based on different mechanistic regulatory scenarios varied widely: a model with local and regional dynamics estimated a lower metapopulation capacity (645,655 AOS) and consequently higher present saturation (63 %) than a model with local density dependence (1,367,352 AOS, 34%). Our findings suggest that metapopulation regulation in the gannet is more complex than traditionally assumed, and highlight the importance of using models that consider colony connectivity and regional dynamics for conservation management applications guided by precautionary principles. Our study advances our understanding of metapopulation dynamics in long-lived colonial species and our approach provides a template for the development of metapopulation models for colonially living birds and mammals