Breeding Patches Research Articles

Dealing With Assumptions and Sampling Bias in the Estimation of Effective Population Size: A Case Study in an Amphibian Population.

Accurately estimating effective population size (N e) is essential for understanding evolutionary processes and guiding conservation efforts. This study investigates N e estimation methods in spatially structured populations using a population of moor frog (Rana arvalis) as a case study. We assessed the behaviour of N e estimates derived from the linkage disequilibrium (LD) method as we changed the spatial configuration of samples. Moor frog eggs were sampled from 25 breeding patches (i.e., separate vernal ponds, ditches or parts of larger fens) within a single population, revealing an isolation-by-distance pattern and a local spatial genetic structure. Varying buffer sizes around each patch were used to examine the impact of sampling window size on the estimation of effective number of breeders (N b). Our results indicate a downward bias in LD N b estimates with increasing buffer size, suggesting an underestimation of N b. The observed bias is attributed to LD resulting from including genetically divergent individuals (mixture-LD) confounding LD due to drift. This emphasises the significance of considering even subtle spatial genetic patterns. The implications of these findings are discussed, emphasising the need to account for spatial genetic structure to accurately assess population viability and inform conservation efforts. This study contributes to our understanding of the challenges associated with N e estimation in spatially structured populations and underscores the importance of refining methodologies to address population-specific spatial dynamics for effective conservation planning and management.

Lifetime breeding-site and nest-site fidelity in a declining terrestrial toadlet: evidence for a win-stay/lose-shift strategy

IntroductionBreeding-site fidelity can occur at various spatial scales and can vary in strength across these scales. Understanding this variation, and rules governing individual site-fidelity decisions, can have important implications for the conservation and management of threatened species. Globally, amphibians are in rapid decline and breeding-site fidelity appears to be widespread, yet few studies have investigated patterns of lifetime breeding-site fidelity, and no studies have explored decision-making rules in situ.MethodsWe investigated lifetime patterns of breeding site fidelity in the brown toadlet Pseudophryne bibronii, a species displaying population declines and local extinction throughout its range. We monitored a single population for a period spanning 10 years to establish the extent that males express site fidelity at the scale of the breeding site and the breeding patch. We also examined male nest-site fidelity between breeding years in relation to mating success to examine if toadlets follow a Win-stay/Lose shift strategy.ResultsOverall, we found that males displayed extreme lifetime fidelity to specific breeding patches within the breeding site, but that males regularly moved nest-site locations between breeding years. The degree of nest-site fidelity was related to male-mating success, whereby successful males established nests closer to a previous years’ nest location than unsuccessful males.DiscussionOur findings suggest that brown toadlets display extreme site fidelity at the scale of the breeding patch, but that within patches male nesting decisions are flexible and follow a win-stay/lose-shift strategy. These results provide novel evidence that breeding site fidelity in amphibians can vary depending on spatial scale (indicative of scale-dependent information use) and that a rule-based learning strategy can influence the degree of nest-site fidelity. Breeding patch fidelity and capacity for spatial learning may be widespread in long-lived amphibians and necessitate in situ conservation strategies that protect known breeding patches (and adjacent habitat) whilst enabling unconstrained localised movement.

Use of Human Dominated Landscape as Connectivity Corridors among Fragmented Habitats for Wild Asian Elephants (Elephas maximus) in the Eastern Part of Thailand

Habitat fragmentation due to human activities creates threats to wild Asian elephants (Elephas maximus) and increases human-elephant conflicts (HEC). This study analyzed connectivity maps among the core habitats of wild elephants in the eastern part of Thailand. Resistance surfaces, associated with geographic and land use features, were used to estimate the dispersal of wild elephants. An increase in roads, reservoirs, and agricultural areas in 2020 was noted. In addition, the increase of artificial water sources and roads has increased HEC. To reduce HEC, the study of suitable landscape corridors for wild Asian elephants can guide the development of effective connectivity among the habitat patches. The scattered locations of reserved forests induce wild elephants to enter agricultural areas. In 2020, during the dry season, wild elephants used 3552 habitat patches, 253 population patches (4875 km2), 8 breeding patches (68.1 km2), and 253 other patches (193.9 km2). However, habitat patches were reduced to 1961 patches (3850.9 km2) in the wet season. The 16 suitable corridors were recommended for connecting the finest wild Asian elephants. These suitable corridors can be used as a guideline to construct effective landscape corridors for wild Asian elephants’ movement among the habitat patches. This finding can help the local managers and villagers incorporate and design restoration areas for the movement and survival of wild Asian elephants and develop suitable areas for agricultural purposes.

Wildfire influences individual growth and breeding dispersal, but not survival and recruitment in a montane amphibian

AbstractGlobal wildfire regimes are changing rapidly, with widespread increases in the size, frequency, duration, and severity of wildfires. Whereas the effects of wildfire on ecological state variables such as occupancy, abundance, and species diversity are relatively well documented, changes in population vital rates (e.g., survival, recruitment) and individual responses (e.g., growth, movement) to wildfire are more limited because of the detailed information needed on the same individuals both pre‐ and post‐fire. We capitalized on the 2018 Roosevelt wildfire, which occurred during our 6‐year (2015–2020) capture–mark–recapture study of boreal toads (Anaxyrus boreas boreas; n = 1415) in the Bridger‐Teton National Forest, USA, to evaluate the responses of population vital rates and individual metrics to wildfire. We employed robust design capture–recapture models to compare the growth, dispersal, survival, and recruitment of adult boreal toads pre‐ and post‐fire at burned versus unburned sites. At burned locations, growth increased 2 years post‐fire compared with the year directly following wildfire and was higher 2 years post‐fire than any other interval during our study period. Boreal toads dispersed to alternative breeding patches more at burned sites than unburned sites and dispersal increased 2 years post‐fire compared with the year directly following wildfire. Annual survival and recruitment neither differed between pre‐ and post‐fire years nor among pre‐fire years, the year following wildfire, and 2 years post‐fire. We demonstrate that, in certain contexts, dispersal can play a major role in changes to state variables (e.g., abundance) after wildfire, as opposed to other vital rates such as survival and recruitment. Our study represents an important step toward understanding the biological processes that underlie observed patterns in state variables following wildfire, which ultimately will be critical for the effective management of species in landscapes experiencing shifts in fire activity.

136 Application of Ear-attached Sensor Technology (CowManager) to Detect Estrus in a Commercial Beef Cow AI Program

Abstract The CowManager (Agis, Harmelen, the Netherlands) ear sensor technology was developed for dairy cows in confinement and has recently been adopted for pastured beef cows. The sensors fit around the ‘840’ RFID button and houses a 3-dimensional accelerometer that registers movement of the cow’s ear. Each sensor stores up to 7 d of internal data at a time and is transmitted by solar powered routers in the pasture. The objective was to determine the effectiveness of the CowManager system’s estrus detection (ED) feature in beef cows during estrous synchronization (ES), AI, and during exposure to bulls for 60 d. Fifty 6-8 yr multiparous commercial Angus-crossbred cows with calves, were fitted with CowManager ear sensors for 14 d to allow for acclimation. Cows then underwent ES using a 6-d CO-Synch + controlled internal drug release (CIDR) protocol with AI at 72 h post CIDR + prostaglandin F2α with sexed female semen. Estrus detection was determined using breeding patches (Estrotect™, Rockway Inc., Spring Valley, WI), with estrus classified as greater than 50% of color rubbed off, and CowManager sensors with a notification to a smartphone and/or computer. The CowManager sensors were effective in determining estrus in 92% (46/50) of the synchronized cows, and the first service conception rate was 74% (37/50). CowManager sensors detected 100% (37/37), and ESTROTECT patches detected 91% (34/37) of the cows in estrus that conceived by AI. During bull exposure, CowManager detected 100% (13/13) of estrus and the natural breeding dates were confirmed by ultrasound fetal aging. ESTROTECT patches were not used during exposure to bulls. However, CowManager detected 5 of the AI pregnant cows as in estrus during the exposure to bulls. CowManager’s ED feature was highly effective in determining estrus for beef cattle and was similar to breeding patches for ED.

Genetic differentiation in an endangered and strongly philopatric, migrant shorebird

BackgroundPopulations living in fragmented habitats may suffer from loss of genetic variation and reduced between-patch dispersal, which are processes that can result in genetic differentiation. This occurs frequently in species with reduced mobility, whereas genetic differentiation is less common among mobile species such as migratory birds. The high dispersal capacity in the latter species usually allows for gene flow even in fragmented landscapes. However, strongly philopatric behaviour can reinforce relative isolation and the degree of genetic differentiation. The Southern Dunlin (Calidris alpina schinzii) is a philopatric, long-distance migratory shorebird and shows reduced dispersal between isolated breeding patches. The endangered population of the Southern Dunlin breeding at the Baltic Sea has suffered from habitat deterioration and fragmentation of coastal meadows. We sampled DNA across the entire population and used 12 polymorphic microsatellite loci to examine whether the environmental changes have resulted in genetic structuring and loss of variation.ResultsWe found a pattern of isolation-by-distance across the whole Baltic population and genetic differentiation between local populations, even within the southern Baltic. Observed heterozygosity was lower than expected throughout the range and internal relatedness values were positive indicating inbreeding.ConclusionsOur results provide long-term, empirical evidence for the theoretically expected links between habitat fragmentation, population subdivision, and gene flow. They also demonstrate a rare case of genetic differentiation between populations of a long-distance migratory species. The Baltic Southern Dunlin differs from many related shorebird species that show near panmixia, reflecting its philopatric life history and the reduced connectivity of its breeding patches. The results have important implications as they suggest that reduced connectivity of breeding habitats can threaten even long-distance migrants if they show strong philopatry during breeding. The Baltic Southern Dunlin warrants urgent conservation efforts that increase functional connectivity and gene flow between breeding areas.

Informed breeding dispersal following stochastic changes to patch quality in a pond-breeding amphibian.

The unidirectional movement of animals between breeding patches (i.e. breeding dispersal) has profound implications for the ecological and evolutionary dynamics of spatially structured populations. In spatiotemporally variable environments, individuals are expected to adjust their dispersal decisions according to information gathered on the environmental and/or social cues that reflect the fitness prospects in a given breeding patch (i.e. informed dispersal). A paucity of empirical work limited our understanding of the ability of animals to depart from low-quality breeding patches and settle in high-quality breeding patches. We examined the capacity of individuals to respond to stochastic changes in habitat quality via informed breeding dispersal in a pond-breeding amphibian. We conducted a 5-year (2015-2019) capture-recapture study of boreal toads Anaxyrus boreas boreas (n=1,100) that breed in beaver ponds in western Wyoming, USA. During early spring of 2017, an extreme flooding event destroyed several beaver dams and resulted in the loss of breeding habitat. We used multi-state models to investigate how temporal changes in pond characteristics influenced breeding dispersal, and determine whether movement decisions were in accordance with prospects for reproductive fitness. Boreal toads more often departed from low-quality breeding ponds (without successful metamorphosis) and settled in high-quality breeding ponds (with successful metamorphosis). Movement decisions were context-dependent and associated with pond characteristics altered by beaver dam destruction. Individuals were more likely to depart from shallow ponds with high vegetation cover and settle in deep ponds with low vegetation cover. The probability of metamorphosis was related to the same environmental cues, suggesting that boreal toads assess the fitness prospects of a breeding patch and adjust movement decisions accordingly (i.e. informed breeding dispersal). We demonstrated that stochastic variability in environmental conditions and habitat quality can underpin dispersal behaviour in amphibians. Our study highlighted the mechanistic linkages between habitat change, movement behaviour and prospects for reproductive performance, which is critical for understanding how wild animals respond to rapid environmental change.

Warming threatens habitat suitability and breeding occupancy of rear‐edge alpine bird specialists

Alpine ecosystems are particularly vulnerable to climate change. For widely distributed alpine specialists, rear‐edge populations are disproportionately important; it is expected that climate change will reduce their occupancy ranges due to the loss of suitable habitats and connectivity among them. Using four alpine bird species inhabiting the southwestern Palearctic as models, we aim to study which and how environmental factors influence habitat suitability, identify mountain areas with suitable habitat, estimate the probabilities of hosting breeding populations for these areas, and predict how habitat suitability and breeding occupancy will change under future climate scenarios. We used a species distribution modeling approach to obtain habitat suitability maps for four biological seasons and assessed the importance and effects of climatic and landscape variables for the studied species. We also assessed the probability of occupancy of potential breeding patches using available systematic distribution data, and projected our habitat suitability and occupancy models to future climate conditions. Our results indicated that the habitat suitability of rear‐edge alpine specialists was limited mainly by climatic factors, restricting their suitable areas to the highest mountains where cold climate persist. The actual occupancy of the potential breeding patches was determined by their size, landscape connectivity and habitat quality. For the period 2041–2060 we predicted a substantial reduction of suitable habitats that varied across seasons and species, and a breeding occupancy range loss that varied across mountain ranges and species. Thus, these alpine bird species, currently not considered as threatened, merit a review of their conservation status. Common distribution patterns and potentially similar responses to climatic change suggest that our findings might be applicable for other rear‐edge alpine species. Our study identified specific mountain systems where research and conservation efforts should focus for the conservation of alpine biodiversity in the southwestern Palearctic.

Extreme site fidelity as an optimal strategy in an unpredictable and homogeneous environment

Abstract Animal site fidelity structures space use, population demography and ultimately gene flow. Understanding the adaptive selection for site fidelity patterns provides a mechanistic understanding to both spatial and population processes. This can be achieved by linking space use with environmental variability (spatial and temporal) and demographic parameters. However, rarely is the environmental context that drives the selection for site fidelity behaviour fully considered. We use ecological theory to understand whether the spatial and temporal variability in breeding site quality can explain the site fidelity behaviour and demographic patterns of Gunnison sage‐grouse (Centrocercus minimus). We examined female site fidelity patterns across multiple spatial scales: proximity of consecutive year nest locations, space‐use overlap within and across the breeding and brooding seasons, and fidelity to a breeding patch. We also examined the spatial and temporal variability in nest, chick, juvenile and adult survival. We found Gunnison sage‐grouse to be site faithful to their breeding patch, area of use within the patch and generally where they nest, suggesting an “Always Stay” site fidelity strategy. This is an optimal evolutionary strategy when site quality is unpredictable. Further, we found limited spatial variability in survival within age groups, suggesting little demographic benefit to moving among patches. We suggest Gunnison sage‐grouse site fidelity is driven by the unpredictability of predation in a relatively homogeneous environment, the lack of benefits and likely costs to moving across landscape patches and leaving known lek and breeding/brooding areas. Space use and demography are commonly studied separately. More so, site fidelity patterns are rarely framed in the context of ecological theory, beyond questions related to the win‐stay:lose‐switch rule. To move beyond describing patterns and understand the adaptive selection driving species movements and their demographic consequences require integrating movement, demography and environmental variability in a synthetic framework. Site fidelity theory provides a coherent framework to simultaneously investigate the spatial and population ecology of animal populations. Using it to frame ecological questions will lead to a more mechanistic understanding of animal movement, spatial population structuring and meta‐population dynamics. A free Plain Language Summary can be found within the Supporting Information of this article.

Environmentally mediated reproductive success predicts breeding dispersal decisions in an early successional amphibian

Dispersal is a central mechanism in ecology and evolution. Dispersal evolution is driven by a trade-off between costs and benefits, which is influenced by interindividual variability and local environmental conditions (context-dependent dispersal). Many studies have investigated how dispersal decisions may be influenced by environmental factors, including density, predation and interspecific competition. Yet few have attempted to examine how habitat disturbance may affect the dispersal process in spatially structured populations. In early successional species, one might expect individuals to adjust their dispersal decisions based on two main factors that potentially have an influence on reproductive success: patch size and the level of patch disturbance. In this study, we examined how these two factors affect breeding success and dispersal decisions in an early successional amphibian, the yellow-bellied toad, Bombina variegata. To this end, we used capture–recapture data collected on a spatially structured population occupying 28 breeding patches. We took advantage of recent developments in multievent capture–recapture models to detect signs of context-dependent dispersal. The results revealed that the probability of successful reproduction and the number of newly metamorphosed individuals increased with both the size and the proportion of disturbance of a patch. In addition, our results showed that the factors affecting breeding success also influenced breeding dispersal probability. Large patch size negatively influenced emigration probability; in contrast, it positively influenced immigration probability. Equally, higher disturbance had a strong negative influence on emigration probability and slightly positively affected immigration probability. These findings strongly suggest that individuals make context-dependent dispersal decisions, adjusted to maximize future fitness prospects in a patch, allowing them to better cope with rapid changes in environmental conditions resulting from the ecological succession process. This opens new areas of potential research into the role of dispersal in organism specialization along an ecological succession gradient.

Isolating the roles of movement and reproduction on effective connectivity alters conservation priorities for an endangered bird

Movement is important for ecological and evolutionary theory as well as connectivity conservation, which is increasingly critical for species responding to environmental change. Key ecological and evolutionary outcomes of movement, such as population growth and gene flow, require effective dispersal: movement that is followed by successful reproduction. However, the relative roles of movement and postmovement reproduction for effective dispersal and connectivity remain unclear. Here we isolate the contributions of movement and immigrant reproduction to effective dispersal and connectivity across the entire breeding range of an endangered raptor, the snail kite (Rostrhamus sociabilis plumbeus). To do so, we unite mark-resight data on movement and reproduction across 9 years and 27 breeding patches with an integrated model that decomposes effective dispersal into its hierarchical levels of movement, postmovement breeding attempt, and postmovement reproductive success. We found that immigrant reproduction limits effective dispersal more than movement for this endangered species, demonstrating that even highly mobile species may have limited effective connectivity due to reduced immigrant reproduction. We found different environmental limitations for the reproductive component of effective dispersal compared with movement, indicating that different conservation strategies may be needed when promoting effective dispersal rather than movement alone. We also demonstrate that considering immigrant reproduction, rather than movement alone, alters which patches are the most essential for connectivity, thereby changing conservation priorities. These results challenge the assumption that understanding movement alone is sufficient to infer connectivity and highlight that connectivity conservation may require not only fostering movement but also successful reproduction of immigrants.

Demographic response to patch destruction in a spatially structured amphibian population

Abstract Economic activities such as logging and mineral extraction can result in the creation of new anthropogenic habitats that host specific biodiversity, including protected species. However, the legislation in many Western European countries requires the rehabilitation of “damaged” areas following logging and mining operations, which can eliminate these early successional habitats. Conservation managers face a dilemma in these situations, but often lack knowledge about the impacts of environmental rehabilitation on the population dynamics of pioneer species and so are unable to take this into account in their actions. We investigated the demography of a spatially structured population of an endangered amphibian (Bombina variegata) that uses waterbodies created by logging activities as breeding sites. Using capture–recapture (CR) data collected during a 9‐year study period, we examined how the destruction of breeding patches due to environmental rehabilitation affected adult survival and the long‐term population growth rate. For this purpose, we used recently developed capture–recapture multievent models to estimate survival and dispersal rates in the spatially structured population. We then used these estimates to simulate population trajectories and viability depending on differing frequency of breeding patch destruction. The multievent models revealed that dispersal not resulting from patch loss was relatively high and was sex biased. They also highlighted that patch destruction had a negative impact on adult survival. Moreover, simulations showed that the increase in patch destruction frequency had a strong negative influence on the population growth rate, even when the number of patches remained constant over time. This impact was intensified if female fecundity was also affected. Synthesis and applications. Our study quantifies for the first time the detrimental effect of habitat rehabilitation on the population dynamics of an endangered, pioneer species. Our results show that this deleterious impact of patch destruction could be reduced by certain management practices, such as avoiding the systematic rehabilitation of the breeding patches and compensating for patch destruction by creating substitute breeding patches.

Predator arrival elicits differential dispersal, change in age structure and reproductive performance in a prey population

Predators are an important ecological and evolutionary force shaping prey population dynamics. Ecologists have extensively assessed the lethal effects of invasive predators on prey populations. However, the role of non-lethal effects, such as physiological stress or behavioural responses like dispersal, has been comparatively overlooked and their potential population effects remain obscure. Over the last 23 years, we developed a mark-recapture program for the Audouin’s gull and an intensive carnivore monitoring program to assess how the appearance and invasion of the study site by carnivores affects population dynamics. We evaluate changes in turnover of discrete breeding patches within the colony, age structure and breeding performance. Once carnivores entered the colony, the number of occupied patches increased, indicating a higher patch turnover. Breeders responded by moving to areas less accessible to carnivores. More importantly, the presence of carnivores caused differential (and density-independent) breeding dispersal: experienced, better-performing breeders were more likely to leave the colony than younger breeders. This differential dispersal modified the age structure and reduced the reproductive performance of the population. Our results confirm the importance experience in the study of populations. The role of differential dispersal for animal population dynamics might be more important than previously thought, especially under scenarios of global change.

Habitat suitability and connectivity for an endangered brown bear population in the Iranian Caucasus

Context The identification of suitable habitats and the assessment of connectivity are important to preserve key areas for small isolated, endangered populations. The brown bear, Ursus arctos, needs connectivity to supply the primary habitat requirements including food, water, shelter and space and to provide gene flow among all populations in the Iranian Caucasus. Aims In the present study, we investigated the status and habitat requirements of an endangered brown bear population within the Iranian Caucasus. Methods We applied an approach of consensus species distribution modelling to estimate the distribution of suitable habitats for brown bears using uncorrelated environmental variables. We then used the concept of circuit theory on resultant breeding patches to evaluate regional patterns of connectivity among these patches. Key results We predicted that ~9.10% of the study area is suitable for the brown bear at present. Ten patches (7.95% of the study area) were detected as suitable for breeding populations, where some populations are not able to survive without connectivity. The results indicated that habitat connectivity is sometimes widely affected by a high concentration of human activities such as roads, settlements and mining activities. Our findings showed that existing conservation areas could not safeguard the connectivity of brown bear habitats across the Iranian Caucasus. Conclusions Our results can help target fine-scaled planning approaches for the maintenance of bear meta-population structure, as well as facilitate the movement of individuals by protecting different landscape features. Implications The populations of brown bear are among the first to be harmed by the loss of habitat and connectivity, and, thus, this species is an appropriate focal species for linkage design that is beneficial for threatened populations of other co-existing species such as Persian leopard, grey wolf and Eurasian lynx. Moreover, the brown bear is among the most popular flagship species for conservation planning, which might increase public support for the restoration of habitat and linkages.

Testing the link between perceived and actual risk of predation: mosquito oviposition site selection and egg predation by native and introduced fish

SummaryAccording to the threat‐sensitivity hypothesis, prey avoidance behaviour should reflect the magnitude of predation risk. Since predation can strongly affect reproduction success, ovipositing females are expected to adaptively adjust their predator avoidance response, or local breeding patch selectivity, in accordance with the perceived level of threat posed for their progeny by specific predators. However, association between avoidance and predation can be disrupted when the prey and the predator lack spatiotemporal opportunities to co‐evolve, such as in cases of non‐native predator introductions.We examined the interactions between mosquitoes (from the genusCulex) and three species of sympatric predaceous freshwater fish, a native cyprinidBarbus paludinosus, a cichlidPseudocrenilabrus philanderand an introduced poeciliid, the western mosquitofishGambusia affinis.In an outdoor mesocosm experiment, we quantified patterns ofCulexoviposition site selection across fish species using free‐roaming, caged and fish‐free treatments. In a complementary laboratory experiment, we tested the effectiveness of each fish species as predators of mosquito eggs and larvae.Synthesis and applications. We found evidence for: (i) mosquito egg raft predation by free‐roaming fish; (ii) fish‐specific avoidance by ovipositingCulex; and (iii) a positive association between fish‐specific oviposition avoidance and fish‐specific efficiency as an egg predator. These results contribute towards a better understanding of predator–prey co‐evolution, predator‐borne cue recognition, and suggest local native fish, the southern mouthbrooderPseudocrenilabrus philander, as an alternative toGambusiafor the biocontrol ofCulexmosquitoes.

Nestling diet optimization and condition in relation to prey attributes and breeding patch size in a patch-resident insectivorous passerine: an optimal continuum and habitat constraints

Direct observational studies are needed to address dietary adjustment in species breeding in isolated non-forest habitat islands with respect to the energy demands of growing nestlings and breeding patch size. Using new dietary records determined for nestlings of Whinchat Saxicola rubetra, a dramatically declining insectivorous passerine and an indicator species of the cessation of agricultural activity, we investigated the relationships between changes in the main dietary characteristics, numerical and biomass contributions of major taxonomic and functional prey groups (expressing chitin content, vertical distribution, habitat preference and vagility within the landscape) and brood age, nestling condition and size of abandoned fields (i.e. breeding patches). Broods from larger abandoned fields received more sedentary and heavier prey like Orthoptera and soil-dwelling invertebrates, whereas the proportion of caterpillars, aerial insects and prey from vegetation decreased with increasing patch size. Nestling condition was positively correlated with the proportion of caterpillars and Orthoptera or sedentary prey taxa, but negatively with the proportion of Coleoptera or vagile prey taxa in the diet, though not with patch area. This suggests that parent Whinchats can overcome the habitat constraints resulting from the small area of an abandoned field by interchangeably incorporating the two major prey groups (Orthoptera or Lepidoptera) into the diet they feed to their nestlings. This implies a continuum in dietary optimization that is a trade-off between a brood’s nutritional demands and the parents’ ability to deliver top-ranked invertebrates present mostly within the breeding patch.

Breeding failure induces large scale prospecting movements in the black-legged kittiwake

Before making dispersal decisions, many species are known to gather social information by prospecting potential future breeding sites, especially when they have failed breeding. So far, the role of current breeding performance on the occurrence of prospecting movements has mainly been studied at limited spatial scales, because of difficulties in tracking free-ranging, fast-moving individuals between distant breeding patches. Little information is thus available on individual behaviour and the spatial extent of prospecting movements in response to breeding failure. To address this issue, black-legged kittiwakes which breeding success was manipulated were tracked with GPS at the end of incubation in two Norwegian colonies. Crucially, and as predicted, prospecting visits to other breeding colonies were recorded in 33% of artificially-failed breeders, but never in successful ones. They occurred at large (40km) as well as local spatial scales (1km). Time-budgets of successful and failed breeders differed significantly in terms of trip duration, but also foraging, resting and nesting propensities. These results provide important elements to assess trade-offs between prospecting and other activities. They show that a substantial proportion of failed breeders prospect as early as within a week after failure at the egg stage and suggest that these individuals assess their options of future reproduction by prospecting alternative areas, although dispersal decisions may also involve more complex behavioural processes. Because they link breeding colonies situated tens of kilometres apart, prospecting movements may have critical implications for the dynamics of subdivided populations.

When to stay, when to disperse and where to go: survival and dispersal patterns in a spatially structured seabird population

Dispersal is a key process for the population dynamics of spatially structured populations (at local and metapopulation levels), so the understanding of the mechanisms underlying the movement of individuals in space and time is important for evolutionary and ecological studies. Here we analyzed, for the first time, a long‐term (1992–2009) multi‐site capture– recapture database collected at four local populations of a long‐lived seabird, the Audouin’s gull Larus audouinii, covering 90% of its total world population. Those local populations show different ecological and demographic features that allow us to assess the influence of several key factors involved in breeding dispersal patterns at large spatio‐temporal scales. A recently developed analytical tool in mark–recapture modelling, the multi‐event approach, allowed us to obtain separate departure and settlement probabilities and test different biological hypotheses for each step of the dispersal process. Our results revealed that site fidelity was the most common strategy among breeders, and dispersal was only high from the site with the lowest population size and habitat quality. However, departures from the two largest local populations increased over the study period in response to severe ecological perturbations. Dispersers chose different settlement patches depending on their site of origin, with settlement choices determined by the population size of the destination colony rather than by the local reproductive performance, foraging area (a proxy of food availability) or distance to the destination site. Our results indicate that a breeding site is not abandoned by breeders unless a series of cumulative perturbations occur; once dispersing, settlement is directed towards densely populated sites, with dispersers using population size to rapidly assess the quality of the breeding patch.

The consequences of being colonial: Allee effects in metapopulations of seabirds

Most seabirds live in large colonies. This fact signifies that there is an advantage in living and breeding together. Four explanations are put fore ward for this colonial behaviour, more birds have: (1) a reduced per capita predation of chicks in colonies, (2) a better anti-predator defence, (3) a more efficient foraging in temporally patchy environments and (4) sex ratios that are more likely to be close to one. These factors induce a strong Allee-type density-dependent relation, a positive relation between density and population growth rate at low density. Nevertheless, these Allee effects are generally ignored in seabird population studies. Therefore we study the consequences of introducing Allee-type density-dependent relations in a spatially explicit metapopulation model for the Common Tern ( Sterna hirundo). Simulations show that Allee effects might be responsible for a 20-fold decline in the recolonization distances, causing patches and parts of metapopulations to effectively become more isolated. This leads to long recolonization times of empty breeding patches which consequently cause slower metapopulation expansion and recovery. Additionally, we show that the typical early warning signals, that show that a population is near its critical threshold induce by Allee effects, is less pronounced in colonies that are part of a metapopulation. Hence, we offer some simple equations to estimate critical densities and thresholds in a colony.

Genetic structure reflects natal dispersal movements at different spatial scales in the blue tit, Cyanistes caeruleus

The study of the genetic consequences of dispersal is a central topic in evolutionary, conservation and behavioural research. However, few studies have simultaneously considered dispersal movements from marked individuals and contemporary patterns of gene flow. We analysed the link between dispersal behaviour and gene flow in four populations of blue tits with different degrees of connectivity. For this purpose, we monitored four breeding patches and used genotypic and captureemarkerecapture data to study the genetic consequences of dispersal at different spatial scales. Data on natal dispersal movements revealed that both males and females dispersed less than expected under a random pattern of settlement at the two large spatial scales considered: the whole study area and the two main localities. However, natal dispersal distance was lower than expected under random settlement within natal patches in males whereas an opposite pattern was found for females. Accordingly, microsatellite data revealed limited gene flow between the localities studied and an isolation-by-distance pattern of genetic structure that was particularly strong at the large spatial scale (i.e. considering geographically distant breeding patches). Finally, the strong male philopatry was reflected by a stronger genetic structure and a lower admixed ancestry in this sex. Overall, we found evidence that restricted dispersal and fragmentation may have both contributed to reduce interpopulation gene flow at different spatial scales in a forest species and that there is concordance between genetic studies and those based on captureemarkerecapture.