Assessing the importance of artificial nest‐sites in the population dynamics of endangered Northern Aplomado Falcons Falco femoralis septentrionalis in South Texas using stochastic simulation models

Habitat availability might be the most important determinant of success for a species reintroduction programme, making investigation of the quality and quantity of habitat needed to produce self‐sustaining populations a research priority for reintroduction ecologists. We used a stochastic model of population dynamics to predict whether attempts to improve existing breeding territories using artificial nest platforms improved the population growth rate and persistence of a reintroduced population of Northern Aplomado Falcons Falco femoralis septentrionalis in South Texas. We further assessed whether the creation of new territories, i.e. conversion of entire areas to suitable habitat and not simply the erection of nest platforms, would lead to a subsequent increase in the nesting population. Our model was able to reproduce several characteristics of the wild population and predicted the number of breeding pairs per year strikingly well (R² = 0.97). Simulations revealed that the addition of nest platforms improved productivity such that the population would decline to extinction without them but is stable since their installation. Moreover, the model predicted that the increase in productivity due to nest platforms would cause the population to saturate available breeding territories, at which point the population would contain a moderate proportion of non‐territorial birds that could occupy territories if new ones become available. Population size would therefore be proportional to the increase in available territories. Our study demonstrates that artificial nest‐sites can be an effective tool for the management of reintroduced species.     

The role of age of first breeding in modeling raptor reintroductions

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Winter territoriality and its implications for the breeding ecology of White-throated Dippers Cinclus cinclus

Capsule: Pairs of White-throated Dippers Cinclus cinclus which defended winter territories bred earlier than non-territorial individuals, but there was no difference in reproductive success.

Aims: The effect of winter territoriality on breeding ecology has rarely been studied in resident birds. We carried out a preliminary investigation of whether winter territorial behaviour and territory size affect the timing of reproduction, breeding territory size and reproductive success in a riverine bird, the White-throated Dipper.

Methods: We monitored an individually marked population of White-throated Dippers in the UK. Wintering individuals were classified as either territorial or ‘floaters’ according to their patterns of occurrence and behaviour, and their nesting attempts were closely monitored in the subsequent months. Winter and breeding territory sizes were measured by gently ‘pushing’ birds along the river and recording the point at which they turned back.

Results: All birds defending winter territories did so in pairs, but some individuals changed partners before breeding. Territorial pairs that were together throughout the study laid eggs significantly earlier than pairs containing floaters and those comprising territorial birds that changed partners. However, there were no significant differences in clutch size, nestling mass or the number of chicks fledged. There was no relationship between winter territory length and lay date or any measure of reproductive success, although sample sizes were small. Winter territories were found to be significantly shorter than breeding territories.

Conclusion: Winter territoriality may be advantageous because breeding earlier increases the likelihood that pairs will raise a second brood, but further study is needed. Territories are shorter in winter as altitudinal migrants from upland streams increase population density on rivers, but this may also reflect seasonal changes in nutritional and energetic demands.     

Natal dispersal of Whooping Cranes in the reintroduced Eastern Migratory Population

Natal dispersal is a key demographic process for evaluating the population rate of change, especially for long‐lived, highly mobile species. This process is largely unknown for reintroduced populations of endangered avian species. We evaluated natal dispersal distances (NDD) for male and female Whooping Cranes (Grus americana) introduced into two locations in central Wisconsin (Necedah National Wildlife Refuge, or NNWR, and the Eastern Rectangle, or ER) using a series of demographic, spatial, and life history‐related covariates. Data were analyzed using gamma regression models with a log‐link function and compared using Akaike information criterion corrected for small sample sizes (AIC_c). Whooping Cranes released in the ER dispersed 261% further than those released into NNWR, dispersal distance increased 4% for each additional nesting pair, decreased about 24% for males as compared to females, increased by 21% for inexperienced pairs, and decreased by 3% for each additional year of age. Natal philopatry, habitat availability or suitability, and competition for breeding territories may be influencing observed patterns of NDD. Whooping Cranes released in the ER may exhibit longer NDD due to fragmented habitat or conspecific attraction to established breeding pairs at NNWR. Additionally, sex‐biased dispersal may be increasing in this population as there are more individuals from different natal sites forming breeding pairs. As the population grows and continues to disperse, the drivers of NDD patterns may change based on individual or population behavior.     

The role of conservative versus innovative nesting behavior on the 25‐year population expansion of an avian predator

Species ranges often change in relation to multiple environmental and demographic factors. Innovative behaviors may affect these changes by facilitating the use of novel habitats, although this idea has been little explored. Here, we investigate the importance of behavior during range change, using a 25‐year population expansion of Bonelli's eagle in southern Portugal. This unique population is almost exclusively tree nesting, while all other populations in western Europe are predominantly cliff nesting. During 1991–2014, we surveyed nest sites and estimated the year when each breeding territory was established. We approximated the boundaries of 84 territories using Dirichlet tessellation and mapped topography, land cover, and the density of human infrastructures in buffers (250, 500, and 1,000 m) around nest and random sites. We then compared environmental conditions at matching nest and random sites within territories using conditional logistic regression, and used quantile regression to estimate trends in nesting habitats in relation to the year of territory establishment. Most nests (>85%, n = 197) were in eucalypts, maritime pines, and cork oaks. Nest sites were farther from the nests of neighboring territories than random points, and they were in areas with higher terrain roughness, lower cover by agricultural and built‐up areas, and lower road and powerline densities. Nesting habitat selection varied little with year of territory establishment, although nesting in eucalypts increased, while cliff nesting and cork oak nesting, and terrain roughness declined. Our results suggest that the observed expansion of Bonelli's eagles was facilitated by the tree nesting behavior, which allowed the colonization of areas without cliffs. However, all but a very few breeding pairs settled in habitats comparable to those of the initial population nucleus, suggesting that after an initial trigger possibly facilitated by tree nesting, the habitat selection remained largely conservative. Overall, our study supports recent calls to incorporate information on behavior for understanding and predicting species range shifts.     

Genetic rescue in a severely inbred wolf population

Natural populations are becoming increasingly fragmented which is expected to affect their viability due to inbreeding depression, reduced genetic diversity and increased sensitivity to demographic and environmental stochasticity. In small and highly inbred populations, the introduction of only a few immigrants may increase vital rates significantly. However, very few studies have quantified the long‐term success of immigrants and inbred individuals in natural populations. Following an episode of natural immigration to the isolated, severely inbred Scandinavian wolf (Canis lupus) population, we demonstrate significantly higher pairing and breeding success for offspring to immigrants compared to offspring from native, inbred pairs. We argue that inbreeding depression is the underlying mechanism for the profound difference in breeding success. Highly inbred wolves may have lower survival during natal dispersal as well as competitive disadvantage to find a partner. Our study is one of the first to quantify and compare the reproductive success of first‐generation offspring from migrants vs. native, inbred individuals in a natural population. Indeed, our data demonstrate the profound impact single immigrants can have in small, inbred populations, and represent one of very few documented cases of genetic rescue in a population of large carnivores.     

Feeding territoriality and the reproductive consequences in brown skuas<Emphasis Type="Italic"> Catharacta antarctica lonnbergi</Emphasis>

In the maritime Antarctic, brown skuas (Catharacta antarctica lonnbergi) show two foraging strategies: some pairs occupy feeding territories in penguin colonies, while others can only feed in unoccupied areas of a penguin colony without defending a feeding territory. One-third of the studied breeding skua population in the South Shetlands occupied territories of varying size (48 to >3,000 penguin nests) and monopolised 93% of all penguin nests in sub-colonies. Skuas without feeding territories foraged in only 7% of penguin sub-colonies and in part of the main colony. Females owning feeding territories were larger in body size than females without feeding territories; no differences in size were found in males. Territory holders permanently controlled their resources but defence power diminished towards the end of the reproductive season. Territory ownership guaranteed sufficient food supply and led to a 5.5 days earlier egg-laying and chick-hatching. Short distances between nest and foraging site allowed territorial pairs a higher nest-attendance rate such that their chicks survived better (71%) than chicks from skua pairs without feeding territories (45%). Due to lower hatching success in territorial pairs, no difference in breeding success of pairs with and without feeding territories was found in 3 years. We conclude that skuas owning feeding territories in penguin colonies benefit from the predictable and stable food resource by an earlier termination of the annual breeding cycle and higher offspring survivorship.Research licence: Umweltbundesamt Bonn 13.4-94003-1/5-7.     

DNA fingerprinting of captive breeding pairs of lesser white-fronted geese (Anser erythropus) with unknown pedigrees

For a number of decades, the lesser white-fronted goose (Anser erythropus) has been almost-absent from the Fennoscandian fauna and has a current population size of only about 60 breeding pairs, with fewer than 10 pairs in Sweden. During the period 1981–1991 more than 200 young have been reintroduced in northern Sweden. However, the origin and possible relatedness of lesser white-fronted individuals were unknown when the breeding program started. We have used DNA fingerprinting to assess the similarity of 18 individuals, i.e., the entire captive population used for breeding in 1991 and about 60% of the captive population used in 1981–1991. Minisatellite probe 33.15 provided an index for an average similarity of 0.39 between the mates of the 12 breeding pairs used for producing offspring for reintroduction. This is a higher similarity than in natural populations of birds in general but lower than in populations that have passed through serious population bottlenecks. Individuals originating from different breeders are more dissimilar than those from the same breeder. However, the close relationships (similarity, 0.5–0.6) found in a group of five individuals from different breeders show that selecting individuals from different breeding groups is not sufficient to prevent mating between closely related individuals.     

Mate finding, dispersal distances and population growth in invading species: a spatially explicit model

The expansion of populations into new areas is dependent upon dispersal distances and the ability of colonists to find mates. These factors interact through the spatial distribution of individuals. We develop a mechanistic, spatially explicit model to investigate the interaction between dispersal distances and mate finding in expanding populations. At high dispersal distances and low mate finding abilities, population growth was constrained by the inverse density dependent inability of adults to find mates (an Allee effect). In contrast, at low dispersal distances and high mate finding abilities, growth was constrained by the density dependent inability of dispersers to find vacant territories. Population growth was highest in between these extremes. We suggest that these spatial interactions play an important role in the expansion of populations into new areas and that this methodology provides a useful tool for investigating them.     

Male brood provisioning rates provide evidence for inter‐age competition for mates in female Cooper's Hawks Accipiter cooperii

Life history theory predicts that individuals should maximize lifetime reproductive success (LRS) by breeding as soon as they reach sexual maturity, yet many species delay breeding, either because there are insufficient available mates or breeding sites, or because delayed breeding yields higher LRS. Accipitriform species, such as Cooper's Hawk Accipiter cooperii, exhibit both delayed breeding and delayed plumage maturation. However, in certain circumstances, first‐year females in non‐definitive plumage do breed and apparently compete with older females for high‐quality breeding territories. We predicted that these young females are at a competitive disadvantage compared with older females and that older females would have both higher reproductive success and be able to acquire higher quality nesting territories. We conducted brood counts and measured prey delivery rates by male Cooper's Hawks in an expanding urban population located in Albuquerque, New Mexico (USA), to assess our prediction. We found that older females had higher reproductive success, fledging 1.6 more offspring than younger females, and that they occupied territories where males provisioned at higher rates of 0.37 more prey items per 2‐h period. Our results showed that older females fared better than first‐year females but it is unclear if this is the result of passive or active competition. Older females initiated nesting 14.3 days sooner than first‐year females and thus may have filled vacant, high‐quality territories before first‐year females began seeking mates. Additionally, first‐year females were never observed persistently to confront older females for breeding territories, but they did actively compete against each other. First‐year females may defer to older females who, in a direct competitive interaction, would be most likely to prevail. Thus, delayed plumage maturation in Cooper's Hawks may serve to focus competition for nesting territories within age classes.     

Captive breeding and reintroduction of the lesser kestrel Falco naumanni: a genetic analysis using microsatellites

We used microsatellites to assess ongoing captive breeding and reintroduction programs of the lesser kestrel. The extent of genetic variation within the captive populations analysed did not differ significantly from that reported in wild populations. Thus, the application of widely recommended management practices, such as the registration of crosses between individuals in proper stud books and the introduction of new individuals into the genetic pools, has proven satisfactory to maintain high levels of genetic variation. The high rates of hatching failure occasionally documented in captivity can therefore not be attributed to depressed genetic variation. Even though genetic diversity in reintroduced populations did not differ significantly when compared to wild populations either, average observed heterozygosities and inbreeding coefficients were significantly lower and higher, respectively, when compared to the captive demes where released birds came. Monitoring of reproductive parameters during single-pairing breeding and paternity inference within colonial facilities revealed large variations in breeding success between reproductive adults. The relative number of breeding pairs that contributed to a large part of captive-born birds (50–56%) was similar in both cases (28.6 and 26.9%, respectively). Thus, the chances for polygyny (rarely in this study), extra-pair paternity (not found in this study) and/or social stimulation of breeding parameters do not seem to greatly affect the genetically effective population size. Independently of breeding strategies, the release of unrelated fledglings into the same area and the promotion of immigration should be mandatory to counteract founder effects and avoid inbreeding in reintroduced populations of lesser kestrels.     

Natural and anthropogenic influences on the population structure of white‐tailed eagles in the Carpathian Basin and central Europe

European populations of the white‐tailed eagle Haliaeetus albicilla suffered a drastic decline during the 20th century. In many countries, only a few dozen breeding pairs survived or the species disappeared completely. By today, the populations have recovered, naturally or through restocking (e.g. in Scotland or the Czech Republic). In the Carpathian Basin, which is now a stronghold in southern Europe for the species in the southern part of the distribution range with more than 500 breeding pairs, only about 50 pairs survived the bottleneck. This region provides important wintering places for individuals arriving from different regions of Eurasia. In the present study, we investigated 249 DNA samples from several European countries, using 11 microsatellites and mitochondrial control region sequences (499 bp), to answer two main questions: 1) did the Carpathian Basin population recover through local population expansion or is there a significant gene flow from more distant populations as well? 2) Does the Czech population show signs in its genetic structure of the restocking with birds of unknown origin? Our microsatellite data yielded three genetically separate lineages within Europe: northern, central and southern, the latter being present exclusively in the Carpathian Basin. Sequencing of mitochondrial DNA revealed that there is one haplotype (B12) which is not only exclusive to the Carpathian Basin but it is frequent in this population. Our results suggest that in accordance with the presumably philopatric behaviour of the species, recovery of the Carpathian Basin population was mainly local, but some of the wintering birds coming from the northern and central populations contributed to its genetic composition as well. We detected considerably higher proportions of northern birds within the Czech Republic compared to the neighbouring areas, making it likely that parents of the reintroduced birds came from northern populations.     

Variation in breeding success among reintroduced island populations of South Island Saddlebacks Philesturnus carunculatus carunculatus

South Island Saddlebacks Philesturnus carunculatus carunculatus were once found throughout the South Island of New Zealand, but by the early 1960s were confined to the island of Big South Cape, in the extreme south of the country. All subsequent reintroduced populations of South Island Saddlebacks are derived from 36 surviving birds from this relict population. The aim of this study was to compare the breeding success of three recently reintroduced populations of Saddlebacks relative to their distance from, and habitat similarity to, the relict population. The three study islands show a latitudinal cline with Ulva, Breaksea and Motuara Islands located 60, 190 and 810 km north of Big South Cape, respectively. Saddlebacks on Ulva and Breaksea appeared to prefer to establish breeding territories in coastal scrub, the dominant habitat feature of Big South Cape. The area of coastal scrub habitat was much smaller on Motuara, where breeding territories were instead scattered through broadleaf forest habitat. Nesting success, calculated using Mayfield's method, was significantly greater on Ulva (73%) than on Breaksea (32%) or Motuara (19%) owing primarily to higher egg fertility and hatching success. Although egg failure rates were highest on Motuara, the island least similar to Big South Cape, they were also relatively high on Breaksea where the habitat was similar to Ulva and Big South Cape. Therefore, the results only partially support the hypothesis that nesting success should decrease with increasing habitat difference associated with increasing latitudinal distance from the source population. The data from this 1-year study lay the groundwork for examining further hypotheses on the effects of reintroducing endangered species outside their contemporary range, but within their historical range.     

Age‐dependent dispersal and habitat choice in black‐tailed godwits Limosa limosa limosa across a mosaic of traditional and modern grassland habitats

Whether to disperse, and where to, are two of the most prominent decisions in an individual's life, with major consequences for reproductive success. We studied natal and breeding dispersal in the monogamous black‐tailed godwit Limosa limosa limosa in the Netherlands, where they breed in agricultural grasslands. The majority of these grasslands recently changed from wet herb‐rich meadows into well‐drained grassland monocultures, on which godwits have a lower reproductive success. Here we examine habitat selection with a multistate mark–recapture analysis. Habitat transition probabilities between meadows and monocultures were estimated on the basis of 1810 marked chicks and 531 adults during seven years in a 8500 ha study area. Young and adult godwits may differ in habitat selection because: 1) adults may have gained experience from previous nest success where to settle, 2) younger individuals may find it harder to compete for the best territories. Both young and adults moved at a higher rate from the predominant monocultures to meadows than the other way around, thus actively selecting the habitat with better quality. However, dispersal distance of adults was not affected by previous nest success. The average dispersal distance from place of birth of godwits breeding for the first time was ten times larger than that of adult godwits. That godwits breeding in their second calendar year arrived and laid at similar dates and were equally able to select territories in areas with high breeding densities, suggests that young birds were not competitively inferior to adults. Although on monocultures reproduction is insufficient to maintain constant populations, birds sometimes moved from meadows to monocultures. This explains why even after 30 years of land‐use intensification, godwits still breed in low‐quality habitat. The adjustment to changing habitat conditions at the population level appears to be a slow process.     

Genetic analysis of complex demographic scenarios: spatially expanding populations of the cane toad, Bufo marinus

Inferring the spatial expansion dynamics of invading species from molecular data is notoriously difficult due to the complexity of the processes involved. For these demographic scenarios, genetic data obtained from highly variable markers may be profitably combined with specific sampling schemes and information from other sources using a Bayesian approach. The geographic range of the introduced toad Bufo marinus is still expanding in eastern and northern Australia, in each case from isolates established around 1960. A large amount of demographic and historical information is available on both expansion areas. In each area, samples were collected along a transect representing populations of different ages and genotyped at 10 microsatellite loci. Five demographic models of expansion, differing in the dispersal pattern for migrants and founders and in the number of founders, were considered. Because the demographic history is complex, we used an approximate Bayesian method, based on a rejection-regression algorithm, to formally test the relative likelihoods of the five models of expansion and to infer demographic parameters. A stepwise migration-foundation model with founder events was statistically better supported than other four models in both expansion areas. Posterior distributions supported different dynamics of expansion in the studied areas. Populations in the eastern expansion area have a lower stable effective population size and have been founded by a smaller number of individuals than those in the northern expansion area. Once demographically stabilized, populations exchange a substantial number of effective migrants per generation in both expansion areas, and such exchanges are larger in northern than in eastern Australia. The effective number of migrants appears to be considerably lower than that of founders in both expansion areas. We found our inferences to be relatively robust to various assumptions on marker, demographic, and historical features. The method presented here is the only robust, model-based method available so far, which allows inferring complex population dynamics over a short time scale. It also provides the basis for investigating the interplay between population dynamics, drift, and selection in invasive species.     

Evaluating wildlife translocations using genomics: A bighorn sheep case study

Wildlife restoration often involves translocation efforts to reintroduce species and supplement small, fragmented populations. We examined the genomic consequences of bighorn sheep (Ovis canadensis) translocations and population isolation to enhance understanding of evolutionary processes that affect population genetics and inform future restoration strategies. We conducted a population genomic analysis of 511 bighorn sheep from 17 areas, including native and reintroduced populations that received 0–10 translocations. Using the Illumina High Density Ovine array, we generated datasets of 6,155 to 33,289 single nucleotide polymorphisms and completed clustering, population tree, and kinship analyses. Our analyses determined that natural gene flow did not occur between most populations, including two pairs of native herds that had past connectivity. We synthesized genomic evidence across analyses to evaluate 24 different translocation events and detected eight successful reintroductions (i.e., lack of signal for recolonization from nearby populations) and five successful augmentations (i.e., reproductive success of translocated individuals) based on genetic similarity with the source populations. A single native population founded six of the reintroduced herds, suggesting that environmental conditions did not need to match for populations to persist following reintroduction. Augmentations consisting of 18–57 animals including males and females succeeded, whereas augmentations of two males did not result in a detectable genetic signature. Our results provide insight on genomic distinctiveness of native and reintroduced herds, information on the relative success of reintroduction and augmentation efforts and their associated attributes, and guidance to enhance genetic contribution of augmentations and reintroductions to aid in bighorn sheep restoration.     

Genetic consequences of breaking migratory traditions in barnacle geese Branta leucopsis

Cultural transmission of migratory traditions enables species to deal with their environment based on experiences from earlier generations. Also, it allows a more adequate and rapid response to rapidly changing environments. When individuals break with their migratory traditions, new population structures can emerge that may affect gene flow. Recently, the migratory traditions of the Barnacle Goose Branta leucopsis changed, and new populations differing in migratory distance emerged. Here, we investigate the population genetic structure of the Barnacle Goose to evaluate the consequences of altered migratory traditions. We used a set of 358 single nucleotide polymorphism (SNP) markers to genotype 418 individuals from breeding populations in Greenland, Spitsbergen, Russia, Sweden and the Netherlands, the latter two being newly emerged populations. We used discriminant analysis of principal components, F_ST, linkage disequilibrium and a comparison of geneflow models using migrate ‐n to show that there is significant population structure, but that relatively many pairs of SNPs are in linkage disequilibrium, suggesting recent admixture between these populations. Despite the assumed traditions of migration within populations, we also show that genetic exchange occurs between all populations. The newly established nonmigratory population in the Netherlands is characterized by high emigration into other populations, which suggests more exploratory behaviour, possibly as a result of shortened parental care. These results suggest that migratory traditions in populations are subject to change in geese and that such changes have population genetic consequences. We argue that the emergence of nonmigration probably resulted from developmental plasticity.     

A new breeding population of Mediterranean Gulls Larus melanocephalus in the species' main wintering area maintains independent spatial dynamics

We studied a newly established breeding population of the range‐expanding Mediterranean Gull Larus melanocephalus in eastern Spain, situated in close proximity to the species' main wintering area. By investigating the origin, population composition and wintering area of the new breeders, we found that recruitment from locally wintering birds was unlikely and that the emerging colonies were probably attracting birds from populations wintering 700–1200 km away in Portugal and southern Spain. Our findings reveal that expanding populations may follow their own dynamics, independently of other populations of the same species, and may consist of different individuals altogether.     

Nest-site selection by Common Black-Hawks in southwestern New Mexico

ABSTRACT.   Despite the interest of resource managers and conservationists in the status of Common Black-Hawk ( Buteogallus anthracinus ) populations in the southwestern United States, little is known about their nesting success and habitat requirements. Because such information is essential for effective population and habitat management, I examined the nesting success and nest-site selection of Common Black-Hawks in southwestern New Mexico during 2000 and 2001. Of the 37 nesting attempts in 21 territories, ≥1 young fledged from 25 nests (68%). Comparison of nest-sites and nonused sites suggested that breeding Common Black-Hawks selected nest-sites in areas with a sparser and shorter subcanopy tree layer and in trees with a smaller trunk diameter and a greater minimum crown diameter. These differences appear to be related to variation in forest ages within territories, with nonused sites having fewer, but older, canopy trees than nest-sites. Sites with younger, smaller subcanopy trees may provide forest structure for more effective foraging, whereas the characteristics of younger nest tree canopies may reduce the risk of nest predation or offer more protection from inclement weather. Due to the limited range of this species in the southwestern United States, efforts to encourage the establishment and maturation of riparian forests in Common Black-Hawk breeding areas could be important in sustaining available nesting habitat and, in turn, maintaining or expanding current population levels.     

Population expansion and breeding success of Bearded Vultures Gypaetus barbatus in the French Pyrenees: results from long‐term population monitoring

Based on monitoring of Bearded Vultures over 24 years in the French Pyrenees, we assessed factors explaining temporal and spatial variations in numbers and breeding performance. The number of territorial pairs increased throughout the study period from 16 in 1994 to 44 in 2017. No significant negative trends in mean productivity (fledglings per territorial pair) were detected with increasing population size. Colonization probability increased significantly with breeding population size the previous year and with the regular provision of supplementary food in the territory the winter when colonization occurred. Colonization of new territories simultaneously increased the distribution range and local densities, but we found no effect of number of near neighbours on productivity. Pairs having bred less than 5 years together had a much lower probability of laying clutches, and higher lay rates were observed inside or close to protected areas after accounting for pair‐bond length, so productivity of territories inside protected areas was significantly higher. Nest success decreased with advanced lay date and increased with winter food abundance. Nesting failures in the study area were frequently associated with harsh weather. Additionally, disturbance by human activities was the second most important identified cause of breeding failure. The probability of failing due to disturbance was higher in western areas (where breeding areas are more accessible to humans), outside protected areas, and has increased with time. After a failure due to disturbance, there was a significantly higher probability of not producing a clutch the following year as compared with pairs that had not failed or had failed due to other causes, indicating deferred effects of disturbance. Our results show the benefits of conservation management actions, such as implementation of protected areas or designed supplementary food programmes in winter, to help range expansion. On the other hand, we did not find a significant effect of winter supplementary food on productivity. Management of feeding sites should be adapted to more specific planning, being used only in areas where natural food availability is scarce, avoiding its use close to breeding sites when juveniles disperse, and targeted mainly to help range expansion. Our results also highlight the importance of maintaining or enhancing good populations of wild ungulates and regulating human activities around nesting sites of this threatened species.