Natal Site Research Articles

Differences In Sockeye Salmon Antibody Composition: Testing The Immunological Imprinting Hypothesis

Anadromous fish such as sockeye salmon return to their natal streams to spawn, during which they undergo significant physiological changes including the release of cortisol, a known immunosuppressive hormone. Our lab has proposed the Immunological Imprinting Hypothesis, which suggests that juvenile anadromous fish respond to pathogens specific to their natal site by producing protective long lived plasma cells (LLPCs) that constitutively produce antibodies against those pathogens. These LLPCs are believed to be highly cortisol resistant. Thus, fish returning to their natal streams have immunological protection from pathogens found at that specific location. We are investigating the Immunological Imprinting Hypothesis through analysis of antibody composition and usage. Since 2009 samples of Sockeye Salmon spleen and anterior kidney have been harvested from two separate salmon runs in Alaska. Using quantitative PCR (qPCR) we are examining the relative usage levels of specific VH gene families between fish at different locations. To further investigate the “pathogen fingerprint” of given spawning sites, we are also performing qPCR analysis in order to compare the pathogen loads of multiple pathogens from different sites, including Bacterial Kidney Disease (Renibacterium salmoninarum), Bacterial Coldwater Disease (Flavobacterium psychrophilum), and Infectious Hematopoietic Necrosis Virus (IHNV). As we gather more data, we will test whether specific antibody compositions are associated with specific spawning sites, as well as with pathogen infection patterns. Greater understanding of spawning fish immune functioning could potentially suggest a method of natural immunization against common fish pathogens and thus protect both farmed and wild populations.

Photo-ID as a tool for studying and monitoring the endangered Saimaa ringed seal

Photo-identification (photo-ID) with camera traps was examined as a non-invasive method for studying and monitoring the endangered Saimaa ringed seal Phoca hispida saimensis. An average of 51 game cameras were set up at shoreline haul-out sites in central Lake Saimaa during the moulting seasons in each of the years from 2010 to 2014. Individuals were identified from their lifelong unique lateral fur patterns. A total of 220 000 digital images of seals were obtained from these game cameras and from digital cameras during this period, allowing 164 indi- viduals to be identified, 43% of which were re-sighted in successive years. In the majority of game camera images, both sides of the seal were shown, and it was possible to determine the sex of the seal. The average distance between sightings of individual seals in different years was 1.6 km, suggesting that Saimaa ringed seals exhibit a high degree of moulting site fidelity. In addition, the results support suggestions of natal site fidelity. We propose that photo-ID sampling based on camera traps, and larger-scale photographic survey of the seals, should be implemented as a pop- ulation monitoring tool of the Saimaa ringed seal. Further application of the photo-ID technique may facilitate mark-recapture population and survival rate estimates for this threatened seal spe- cies and provide significant insights into its life history and social behaviour.

Nest as an extended phenotype signal of female quality in the great reed warbler

Extended phenotypes with signalling function are mostly restricted to animal taxa that use construction behaviour during courtship displays. However, they can be used also as post‐mating signals of mate quality, allowing individuals to obtain reliable information about their partners. Nest size may have such a signalling function and a lot of indirect evidence supports this view. However, direct evidence based on an experimental approach is still widely missing. Here we test the role of nest size in post‐mating signalling of mate quality in the great reed warbler Acrocephalus arundinaceus, a passerine with female‐restricted nest‐building behaviour. Based on observational data, clutch size, nestling weight, brood size and fledglings’ propensity to return to their natal site positively correlated with nest size. Moreover, we experimentally enlarged great reed warbler nests to investigate whether this manipulation affects male investment in feeding. We found that males fed their nestlings significantly more intensively on enlarged nests than those on control nests. This suggests that nest size in this species serves as a signal of female quality or willingness to invest in reproduction and that it pays males to enhance their feeding effort according to this signal. Thus, we provide convincing evidence that animal communication takes place through the extended phenotypes and that post‐mating signalling of quality is not restricted only to males, but may function equally well in females.

Wherever I may roam: social viscosity and kin affiliation in a wild population despite natal dispersal.

Dispersal affects the social contexts individuals experience by redistributing individuals in space, and the nature of social interactions can have important fitness consequences. During the vagrancy stage of natal dispersal, after an individual has left its natal site and before it has settled to breed, social affiliations might be predicted by opportunities to associate (e.g., distance in space and time between natal points of origin) or kin preferences. We investigated the social structure of a population of juvenile great tits (Parus major) and asked whether social affiliations during vagrancy were predicted by 1) the distance between natal nest-boxes, 2) synchrony in fledge dates, and 3) accounting for spatial and temporal predictors, whether siblings tended to stay together. We show that association strength was affected predominantly by spatial proximity at fledging and, to a lesser extent, temporal proximity in birth dates. Independently of spatial and temporal effects, sibling pairs associated more often than expected by chance. Our results suggest that the structure of the winter population is shaped primarily by limits to dispersal through incomplete population mixing. In addition, our results reveal kin structure, and hence the scope for fitness-related interactions between particular classes of kin. Both spatial-mediated and socially mediated population structuring can have implications for our understanding of the evolution of sociality.

Unusual migratory behaviour in a newly established subpopulation of Whooper Swan (Cygnus cygnus) breeding in the highlands of Poland

The migratory behaviour of a subpopulation of Whooper Swans breeding in highlands of southern Poland was studied over a 17-year period, from 1997 to 2013. Birds ringed in their breeding area spent winters and moulting periods in the vicinity of their natal sites, and the mean distance between breeding area and wintering sites was only 149.1 ± 11.7 km. Moreover, 57.0% of all winter re-sightings were obtained within 100 km of the study area. There was an increase in winter site fidelity by individual Whooper Swans over their lifetime (R 2 = 0.09, p = 0.019), reflected by a linear decrease in the distance travelled between two consecutive winters (b = –0.22 ± 0.09). We did not find any association between winter severity and the birds’ migratory behaviour, neither in the distance travelled nor the location of winter recoveries. The mean distance between the study area and the moulting site was 142.7 ± 34.6 km and c. 66.6% of ring re-sightings during the moulting period were within 100 km of the study area. During autumn many immature birds were observed close to their parents’ breeding territory and this could help them reunite with parents or siblings from other seasons. The apparent reduction of migratory behaviour compared with representatives of northern populations indicates behavioural plasticity in the Whooper Swan, which may facilitate further southward expansions of the species.

Dispersal of the Central European Population of the Eurasian Spoonbill Platalea leucorodia

Summary. Using the Hungarian spoonbill colour-ringing scheme database, which spans 12 years of 11 cohorts (2003–2013), we clarify dispersal patterns of spoonbills in the Carpathian Basin, a part of the Pannonian biogeographical region. We found that during the course of one year, approximately 25% of adult spoonbills disperse and are seen 100 km beyond their natal area. However, this rate is roughly 20% if we analyse only the core of the breeding season (May and June). The extent of dispersal in the Hungarian population is greater than that in the Atlantic population, where the proportion of birds showing natal site fidelity is higher. This finding could be explained by increased unpredictability in the Carpathian Basin in the temporal and spatial distribution of food resources and in the water- supply of wetlands, as well as in conditions at breeding locations there. These factors may also explain the high dispersal rate of adults in continental wetland habitats compared to coastal ones. Furthermore, the...

The potential impacts of migratory difficulty, including warmer waters and altered flow conditions, on the reproductive success of salmonid fishes

Climate change and urbanisation of watercourses affect water temperatures and current flow velocities in river systems on a global scale. This represents a particularly critical issue for migratory fish species with complex life histories that use rivers to reproduce. Salmonids are migratory keystone species that provide substantial economical value to ecosystems and human societies. Consequently, a comprehensive understanding of the effects of environmental stressors on their reproductive success is critical in order to ensure their continued abundance during future climatic change. Salmonids are capital breeders, relying entirely on endogenous energy stores to fuel return migration to their natal spawning sites and reproduction upon arrival. Metabolic rates and cost of transport en-route increase with temperature and at extreme temperatures, swimming is increasingly fuelled anaerobically, resulting in an oxygen debt and reduced capacity to recover from exhaustive exercise. Thermally challenged salmonids also produce less viable gametes, which themselves are affected by water temperature after release. Passage through hydrological barriers and temperature changes both affect energy expenditure. As a result, important energetic tradeoffs emerge between extra energy used during migration and that available for other facets of the reproductive cycle, such as reproductive competition and gamete production. However, studies identifying these tradeoffs are extremely sparse. This review focuses on the specific locomotor responses of salmonids to thermal and hydrological challenges, identifying gaps in our knowledge and highlighting the potential implications for key aspects of their reproduction.

Successful elimination of a lethal wildlife infectious disease in nature.

Methods to mitigate the impacts of emerging infectious diseases affecting wildlife are urgently needed to combat loss of biodiversity. However, the successful mitigation of wildlife pathogens in situ has rarely occurred. Indeed, most strategies for combating wildlife diseases remain theoretical, despite the wealth of information available for combating infections in livestock and crops. Here, we report the outcome of a 5-year effort to eliminate infection with Batrachochytrium dendrobatidis affecting an island system with a single amphibian host. Our initial efforts to eliminate infection in the larval reservoir using a direct application of an antifungal were successful ex situ but infection returned to previous levels when tadpoles with cleared infections were returned to their natal sites. We subsequently combined antifungal treatment of tadpoles with environmental chemical disinfection. Infection at four of the five pools where infection had previously been recorded was eradicated, and remained so for 2 years post-application.

DNA barcoding of Iberian Peninsula and North Africa Tawny Owls Strix aluco suggests the Strait of Gibraltar as an important barrier for phylogeography

Eight subspecies have been proposed within the Tawny Owl (Strix aluco) species. However, recent molecular data have challenged this view, encouraging further work in this species complex. Here we reevaluated the taxonomic status between the North-Western African Tawny Owl, S. a. mauritanica, and its closest Iberian Tawny Owl population (from the S. a. sylvatica to S. a. aluco clade) separated by the Strait of Gibraltar. The Tawny Owl is a non-migratory and territorial species, and juvenile dispersal is restricted to a few kilometers around the natal site. This limited dispersal and the barrier imposed by the Strait of Gibraltar predicted a strong differentiation between the two populations. We tested this using DNA barcoding, Bayesian phylogenetic and species delimitation analysis. We found that an 81.1% of variation is due to the intergroups variation. In addition, the inter–intraspecific distances distribution revealed a barcoding gap among the two subspecies. Also, posterior probabilities and the PAB value allowed to reject the hypothesis that observed degree of distinctiveness is due to random coalescence processes. These findings clearly support the Strait of Gibraltar as an isolating barrier for this species. The subspecific status is confirmed and species status is even suggested for S. a. mauritanica.

A comparison of genetic structure in two low-dispersal crabs from the Wild Coast, South Africa

The Wild Coast in south-eastern South Africa is strongly influenced by the warm, southward-flowing Agulhas Current. This current has a significant impact on dispersal in the coastal biota of the region, and facilitates high levels of connectivity among populations. However, it is not known how the region's high-velocity hydrology affects genetic population structure in endemic estuarine species, populations of which are frequently isolated from the sea. Here, we compared genetic structure in two estuarine crabs of the family Hymenosomatidae. Both are presumed to have low dispersal potential, but they differ in terms of their life histories. Hymenosoma longicrure has abbreviated larval development and can complete its entire life cycle within estuaries, whereas Neorhynchoplax bovis is a direct developer that lacks planktonic larvae. Using DNA sequence data from the mitochondrial COI gene and the intron of the nuclear ANT gene, we found that levels of genetic structure differ considerably between the species. Depending on the genetic marker used, H. longicrure is genetically homogeneous (COI) or displays low levels of genetic structure and minor evidence of recruitment near natal sites (ANT). In contrast, connectivity in N. bovis is much lower, as this species has a unique combination of alleles at each site, indicating that recruitment is mostly local. These results support previous findings suggesting that even a short larval dispersal phase is sufficient to maintain high levels of connectivity and prevent genetic divergence among populations.

Invasion success of a habitat-forming marine invertebrate is limited by lower-than-expected dispersal ability

Species that disperse by means of planktonic larvae are typically not genetically structured along environmentally homogeneous coastlines. In contrast, those that lack a planktonic dispersal phase, or species with a short (<12 h) pelagic propagule duration (PPD), tend to show population genetic structure at small spatial scales, with dispersal often taking place by means of a stepping-stone process. These general patterns emerged in the literature after decades of studies based on relatively poorly resolving genetic markers (e.g. allozymes and DNA se- quences). However, recent evidence based on more informative genetic markers (microsatellites) suggests that stepping-stone dispersal is not uncommon in species with a PPD of days to weeks. Here, we used microsatellite data to investigate genetic structure in a non-native population of the solitary ascidian Pyura doppelgangera in southern Australia. This species is part of a group of mar- ine invertebrates with great potential to become invasive, whose 1 day PPD was considered to be sufficiently long to drive genetic homogeneity along continuous coastlines. We identified genetic structure at scales of a few kilometres, with clear signatures of larval retention at natal sites. This limited dispersal potential may explain why the species has not yet established itself throughout the invaded region. Our results add to the growing evidence that many previous studies may have over-interpreted the dispersal potential of this group, likely because of insufficient resolution of the more slowly evolving DNA markers used to make inferences at ecological time-scales.

Dispersal capacities of anadromous Allis shad population inferred from a coupled genetic and otolith approach

Understanding dispersal capacities for migratory species is crucial for their management. By coupling otolith microchemistry and microsatellite genetic analyses, we provided information on snapshot and long-term dispersal capacity of Allis shad (Alosa alosa), an anadromous clupeid in decline throughout its distribution range. The allocation of natal origin was obtained from water chemistry and signatures in otoliths of juveniles and spawners within a Bayesian model. The majority of adults were assigned to a source river with high degrees of confidence; only 4% were undetermined. Otolith natal origins were used to define a population baseline by grouping individuals from the same natal river and not from the same sampling location as usually done. While A. alosa exhibited a high level of natal site fidelity, this species showed weak genetic structure, which supported the evidence of a substantial flow of strayers between river basins in the vicinity or at longer distances. However, long distance straying was probable but not frequent. In a context of global change, straying would be a key mechanism to drive dispersal and allow resilience of Allis shad populations.

Eurasian lynx natal den site and maternal home‐range selection in multi‐use landscapes of Norway

AbstractIn carnivores, securing suitable den sites with associated early maternal home ranges is important for successful reproduction, and understanding natal den site selection is essential to ensure that these habitats are protected from human disturbance. This study investigated Eurasian lynx Lynx lynx natal den site selection across multiple use landscapes in Norway and explores whether the selection of early maternal home ranges across southern Norway involved a trade‐off of security for access to their preferred prey species, roe deer Capreolus capreolus. The characteristics of natal dens and home ranges from 33 reproductive events were quantified across south‐eastern and northern Norway. Natal dens were located in terrain further from the most accessible and disturbed areas (public roads) and in terrain more rugged than generally available. Early maternal home ranges were characterized by low human and low road density in rugged terrain and a selection for areas associated with higher or lower roe deer densities was not important in our analysis. Humans are the dominant cause of lynx mortality throughout Norway and our findings suggest that female lynx primarily chose areas that limited their interaction with people during the denning period.

How far north are migrant birds transporting the tick Ixodes scapularis in Canada? Insights from stable hydrogen isotope analyses of feathers

Lyme disease is emerging in Canada because of northward range expansion of the tick vector Ixodes scapularis. It is hypothesised that I. scapularis feeding on passerine birds migrating north in spring are important in founding new I. scapularis populations leading to northward range expansion. However, there are no studies on how far north I. scapularis may be carried, only inferences from passive tick surveillance. We used stable hydrogen isotope (δ2H) analysis of rectrices collected from northward migrating, I. scapularis-carrying, passerine birds captured in Canada to estimate how far north I. scapularis may be carried. Rectrices are usually grown close to breeding sites and their δ2H values reflect those in the environment, which vary strongly with latitude in North America. Passerines usually return to their breeding or natal sites so δ2H values of rectrices of northward migrating birds can identify the likely latitudinal bands of their intended destinations. In 2006 we analysed δ2H from rectrices of 73 I. scapularis-carrying birds captured at five migration monitoring stations, mainly from southern Ontario. Values of δ2H ranged from −33 to −124‰, suggesting 19/71 (26.7%) birds were destined for latitude band B (the most southerly part of Ontario), 40/71 (56.3%) birds were destined for band C (which extends from southern Ontario, Quebec and the Maritimes to southern James Bay) and 12/71 (16.9%) birds were destined for bands D and E (which extend from northern Ontario and Quebec into the southern Canadian Arctic). This indicates that many I. scapularis-carrying migratory birds in spring have destinations far north in Canada, including some farther north than the current region of climatic suitability for I. scapularis. These findings support the hypothesis that I. scapularis may continue to be spread north by spring migrating passerines. Some thrush species may be particularly implicated in far northward dispersion of I. scapularis.

Spatial variation in population density affects dispersal behavior in brush mice

Population density can influence all three phases of natal dispersal: departure from the place of birth, searching the landscape, and selecting a new site in which to settle. The direction of the effect of density on dispersal should be affected by the relative costs and benefits of living in an area with high population density. Animals may benefit from high population density due to mate availability and predator risk dilution, but may also face increased competition in high density areas. These conflicting mechanisms should influence the pattern of change in population density between pre‐ and post‐dispersal locations: do dispersing individuals choose to move to areas of higher or lower population density than that at their natal site? We examined the influence of density on dispersal in brush mice (Peromyscus boylii). We documented pre‐ and post‐dispersal locations of individuals using both radio telemetry and live‐trapping, and used a spatially explicit capture–recapture model to estimate density across the landscape. We also tested for a relationship between dispersal distance and local population density at the natal site. Animals tended to settle in areas with higher population densities than where they were born. This pattern held when landscape‐level changes in population density were incorporated: the magnitude of change in local population density between the pre‐ and post‐dispersal locations of a given individual tended to be greater than would be explained by increasing population density across the landscape alone. Further, dispersal distances were shorter when local natal population density was higher.

Life‐history characteristics of ide Leuciscus idus in the Eastern Baltic Sea

AbstractOtolith Sr:Ca and Ba:Ca profiles were used in parallel with age data to investigate the life‐history characteristics of ide, Leuciscus idus (L.) (n = 111), in the Väinameri Sea, West Estonia. Sr:Ca profiles were more variable and useful than Ba:Ca profiles. Flexible life‐history patterns were observed within and among the three study sites. Most of the individuals (72%) hatched in semi‐enclosed bays that are fresh water during spring spawning but are often flooded with brackish water during other seasons. The importance of lotic spawning varied among sites and was the highest (88%) in Matsalu Bay, moderate in Saunja Bay (33%) and lowest (0%) in Käina Bay. Young of the year emigrated from natal sites and entered the sea within the first summer; 95% did so during the first month post‐hatch. Juvenile ide undertook non‐spawning, freshwater migrations in the following spring; however, the reasons behind this phenomenon remain unknown. As the importance of lotic spawning has significantly decreased and multiple historically important ide spawning rivers lack anadromous runs altogether, it is suggested that actions should be taken to aid the recovery of those imperilled spawning stocks.

How do African Black Oystercatchers Haematopus moquini recruit into high-density populations?

Theoretical and empirical studies of oystercatchers both suggest that levels of adult site fidelity, natal philopatry and age-at-first-breeding are interrelated consequences of life-history decisions made by potential breeders. All are fundamental to explaining population dynamics and have important conservation implications. The African Black Oystercatcher Haematopus moquini is classified as Near Threatened and virtually nothing is known of the biology of sexually mature birds that have yet to become established as breeders (i.e. ‘floaters’). Using an extensive ringing/ recapture/resighting data set from islands off the west coast of South Africa where densities of territorial oystercatchers are very high, this study aimed to explore (1) the degree to which African Black Oystercatchers exhibit natal philopatry, (2) the age at which they enter the breeding population, and (3) the factors that might determine age-at-first-breeding. Both natal site philopatry and adult breeding site fidelity for island-reared birds were high with almost 100% returning to their natal sites. There is a clear, age-based recruitment pattern of oystercatchers into the island breeding populations, but time spent at a site, rather than age per se, may determine a bird's success in establishing a territory.

Migration strategies revealed by satellite tracking among descendants of a population of European white stork (Ciconia ciconia) reintroduced to Belgium

Migration in the European white stork (Ciconia ciconia) has historically described a predictable annual cycle. The white stork is extensively distributed across continental Europe, which diverges to eastern and western wintering flyways. Within the western European population, some ring recovery and anecdotal information suggests that birds are giving up their traditional wintering grounds in the Sahel and are remaining in alternative sites in the Iberian Peninsula. Here we report on long-term satellite tracking of juvenile and adult stork collected between 2000 and 2011, whose natal site is in Belgium in the northern range of the western migration path. We identified three distinct migration patterns, two of which diverged from traditional expectations. Juvenile birds showed unique migration profiles both individually across migration cycles and when compared to one another, whereas adults showed consistent migrations but failed to migrate to Africa in any of the years surveyed. Stopover and wintering locations within Iberia were strongly associated with refuse sites or modified agricultural land. Overall, non-traditional migration movements appeared to be most strongly linked to artificial food sources rather than alternate drivers such as climate or habitat.

Post-fledging dispersal and habitat use of a reintroduced population of the Crested Ibis (Nipponia nippon)

BackgroundKnowledge of dispersal movement of birds and their habitat preference during the post-fledging period is fundamental to the understanding of their ecological and evolutionary processes. The Crested Ibis is now being reintroduced to protected sites within its historical range, with the goal of establishing a self-sustaining population that may eventually qualify the species for delisting.MethodsWe carried out an ecological study of post-fledging dispersal and habitat use of a reintroduced population of the Crested Ibis (Nipponia nippon) from 2008 to 2012 in Ningshan County, China, by using banding and radio-telemetry methods.ResultsIn about two weeks (an average of 14.3 days) after fledging, the activities of the fledglings were concentrated in a range of about 100 m around their natal sites, such as the oak-pine forest patches at the edge of open habitats. During this period, fledglings were still partially dependent upon parental care and fed typically on a daily basis. Siblings increasingly became independent by mid-August and then gradually moved away from their natal sites to post-fledging dispersal locations. During the period of the post-fledging dispersal process, most juveniles moving southwest were concentrated at the mean direction (μ = 254.6°, š = 70.5°) with a mean dispersal distance of 5.1 km. It took an average of 56.4 days to disperse from the natal territory to the first wintering area. Also, forging habitats for juvenile ibis varied with time and local conditions. For example, paddy fields were used most frequently among all habitat types, while shallow rivers just from August to October. Masson pine (Pinus massoniana) was often regarded as the roosting tree species preferred by the Crested Ibis, with the highest utilization rate among all the roosting habitat types. The juveniles of the wild population dispersed four times as far as that of the reintroduced population, but the overall pattern of post-fledging dispersal is similar for the reintroduced and wild populations.ConclusionsOur results are very useful for us to predict the distance and direction of dispersal under various landscape conditions in other released sites. The project is a good example for reintroducing endangered species to their former ranges, and will be valuable for the protection of reintroduced populations of this critically and other endangered species.

Effects of sex and population density on dispersal and spatial genetic structure in brush mice

Natal dispersal, the process of moving between the natal site and the site of 1st reproduction, affects a variety of ecological and evolutionary processes. Multiple factors have been suggested to influence patterns of natal dispersal in vertebrates; sex and population density are 2 of the most frequently invoked. In mammals, males are typically expected to disperse farther or more frequently than females. In contrast, theoretical predictions about the effect of population density are less clear, and support exists for both positive and negative density-dependent dispersal. Here, I investigate the influences of sex and population density on dispersal distances and spatial genetic structure (SGS) in the brush mouse (Peromyscus boylii), using both intensive field surveys and spatial genetic autocorrelation methods. Neither density nor sex affected dispersal distances. I did detect increased genetic structure in females compared to males, a pattern consistent with male-biased dispersal. However, processes other than dispersal can generate SGS, and I suggest that in addition to sex-biased dispersal, these results also could reflect gene dispersal via mating excursions. No clear effect of population density on either dispersal distance or SGS emerged. These results highlight the importance of using multiple methodologies to investigate dispersal.