Breeding Dispersal Probability Research Articles

Reduced survival in a soaring bird breeding in wind turbine proximity along the northern Baltic Sea coast

Wind power plays a vital role in global climate action and plans for new turbines in the Baltic Sea region are underway. However, it is crucial not to overlook the environmental impact on wildlife, which can be difficult to quantify, especially in elusive and hard-to-track species. One of these species is the white-tailed eagle, a conservation success story that faces a significant collision risk with rotor blades, particularly as turbines are being constructed in its coastal habitats. To assess the effect of wind turbines on survival of territorial adults, we genotyped DNA from adult feathers collected at nests between 2010 and 2022. By tracking individuals across years, we measured survival and breeding dispersal in relation to wind turbine presence. Turbines within a 5 km radius of nests were found to reduce annual survival rates by 7.6 %, while resighting probability and breeding dispersal probability were unaffected. The proportion of territories exposed to wind turbines is currently low (4–5 %), mainly because recent construction sites have been further inland. However, future projections suggest an increase in territory exposure, indicating potential for population-level risks. This highlights the need for substantial safety buffers around nest sites (preferably >5 km) to protect the breeding white-tailed eagle population. Currently, a comprehensive understanding of the large-scale impact on the Baltic Sea white-tailed eagle population is lacking. As wind power expands, it is necessary to consider its impact on wildlife and we recommend conducting ongoing environmental assessments to monitor and adapt conservation measures.

Natal dispersal does not entail survival costs but is linked to breeding dispersal in a migratory shorebird, the southern dunlinCalidris alpina schinzii

The costs and benefits of dispersal are often assessed by comparing fitness between dispersing and non‐dispersing individuals. Importantly, individuals that disperse between their natal and first breeding site may subsequently be more likely to disperse between breeding sites compared to those that remained philopatric to their natal site. Such within‐individual consistency in dispersal behaviour can bias local survival estimation, and thus the survival comparison between dispersing and non‐dispersing individuals, if breeding dispersal leads to permanent emigration from the study area. We examined whether adult survival correlates with natal dispersal in a migratory shorebird, the southern dunlinCalidris alpina schinzii, in two isolated patchy populations where permanent emigration is expected to be extremely rare. To assess whether local adult survival could be biased by non‐random breeding dispersal, we analysed between‐patch breeding dispersal probability and quantified within‐individual consistency in dispersal. Among females, natal dispersers were more likely to disperse again as adults compared to non‐dispersers, while no difference was observed in males which were always highly site faithful. Yet, adult survival did not differ between natal dispersing and non‐dispersing individuals in either sex. Breeding dispersal probability was higher in failed compared to successful breeders. Breeding dispersal often resulted in dispersal back to the natal patch, i.e. delayed natal philopatry. Our results suggest no survival costs of dispersal after first reproduction. Despite individual consistency, survival estimates of dispersing individuals were not biased because nearly all available breeding habitat was covered. We show that consistency in dispersal can occur even in site faithful species like the southern dunlin. Studies of the effects of dispersal on survival should therefore account for within‐individual consistency in dispersal if not all available breeding habitat is monitored in open populations. In particular, delayed natal philopatry may lead to biased local survival estimates for immigrants when compared with philopatric individuals.

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.

Effects of breeding success, age and sex on breeding dispersal of a reintroduced population of the Crested Ibis (Nipponia nippon) in Ningshan County, China

Background Breeding dispersal is an important ecological process that affects species’ population dynamics and colonization of new suitable areas. Knowledge of the causes and consequences of breeding dispersal is fundamental to our understanding of avian ecology and evolution. Although breeding success for a wild and reintroduced population of the Crested Ibis (Nipponia nippon) has been reported, the relationships between individuals’ breeding dispersal and their breeding success, age and sex remain unclear.MethodsIbises’ breeding dispersal distance, which is the distance moved by adults between sites of reproduction, was estimated based on the observations of consecutive breeding sites of marked ibis individuals. From observational and capture-recapture data (n = 102) over 9 years, individuals’ breeding dispersal probability in relation to age, sex, and reproductive success was analyzed via a generalized linear mixed effect modeling approach.ResultsOur results show that 55% males and 51% females keep their previous territories following nesting success. Failed breeding attempts increased dispersal probabilities. Both females and males failed in breeding were more likely to disperse with greater distances than successful birds (females: 825 ± 216 m vs 196 ± 101 m, males: 372 ± 164 m vs 210 ± 127 m). Crested Ibis exhibited a female-biased dispersal pattern that the mean dispersal distance of females (435 ± 234 m) was much larger than that of males (294 ± 172 m).ConclusionOur results are fundamental to predict the patterns of breeding dispersal related to reproductive success under different release sites. From the conservation point of view, landscape connectivity between the reintroduced populations should be taken into account in accordance with the distance of breeding dispersal.

Mate and territory availability affect breeding dispersal and divorce in a resident Southern House WrenTroglodytes aedon musculuspopulation

Breeding dispersal is the movement of an individual between breeding attempts and is usually associated with the disruption of the social pair bond, although mates may disperse together as a social unit. In monogamous territorial species, the decision to disperse may be affected by individual attributes such as sex, age and condition of the disperser. However, environmental and social contexts may also play a crucial role in the decision to disperse. We analysed capture‐resighting data collected over 9 years to study breeding dispersal and divorce rates of a Southern House WrenTroglodytes aedon musculuspopulation in South Temperate Argentina. Between‐season dispersal was more frequent than within‐season dispersal, with females dispersing more often than males, both between and within seasons. Both within‐season and between‐season breeding dispersal probability was affected by territory availability, but not by previous breeding success. When the adult sex ratio (ASR) was more skewed towards males, male between‐season dispersal was also affected by mating status, with widowed and single males dispersing more often than paired males. Within‐season divorce increased the reproductive success of females but not males, and was affected by the availability of social partners (with increasingly male‐skewedASR). Our results suggest that territorial vacancies and mating opportunities affect dispersal and divorce rates in resident Southern House Wrens, highlighting the importance of social and environmental contexts for dispersal behaviour and the stability of social pair bonds.

Breeding dispersal of Mexican Spotted Owls in the Sacramento Mountains, New Mexico

ABSTRACT Dispersal is a key process influencing population dynamics and gene flow in species. Despite this, little is known about breeding dispersal in threatened Mexican Spotted Owls (Strix occidentalis lucida), here defined as movement of a non-juvenile owl between territories where it had the opportunity to breed. We observed 28 cases of breeding dispersal during a study of color-banded Mexican Spotted Owls in the Sacramento Mountains, New Mexico, 2003–2011. This represented 4.9% of total opportunities to disperse (n = 575 observed occasions, range = 0–9.0% of owls dispersing per yr). Breeding dispersal probability was greater for single owls and paired owls whose mate disappeared or moved than for paired owls whose mate remained in the original territory, greater for subadult than for adult owls, and greater for owls that failed to reproduce the year prior to dispersing than for owls that reproduced successfully. There was some evidence that dispersal probability was greater for female owls and th...

Breeding dispersal of Eurasian Hoopoes (Upupa epops) within and between years in relation to reproductive success, sex, and age

ABSTRACT. Breeding dispersal is often affected by previous reproductive success, age, and sex. Birds with multiple broods within a season can disperse not only between, but also within, years. Little is known about factors that govern dispersal within a season or how strong it is compared with dispersal between years. We studied breeding dispersal of Eurasian Hoopoes (Upupa epops) in Valais, Switzerland, using capture-recapture data collected over 8 years (n = 712 individuals). We analyzed breeding dispersal probability and distance, both between and within years, in relation to age, sex, and reproductive output, using multistate capture-recapture models and generalized linear models. Between years, females dispersed more often and over longer distances than males (mean distance, females = 1.98 km; males = 0.83 km), but dispersal was only weakly affected by age and previous reproductive success. Dispersal within a year also differed between sexes (mean distance, females = 1.45 km; males = 0.46 km) and var...

Sex‐Biased Dispersal: A Result of a Sex Difference in Breeding Site Availability

Sex-biased dispersal is often explained by assuming that the resource-defending sex pays greater costs of moving from a familiar area. We hypothesize that sex-biased dispersal may also be caused by a sex bias in breeding site availability. In avian resource-defense mating systems, site availability is often more constrained for females: males can choose from all vacant sites, whereas females are restricted to sites defended by males. Using data on breeding dispersal of a migratory passerine, we show that average number of available breeding options and availability of the previous year's territory was greater for males than females. The female bias in site unavailability may explain the female bias in probability of breeding dispersal because there was no sex bias in dispersal among birds with their previous year's territory available. We suggest that sex biases in the availability of breeding options may be an important factor contributing to observed variation in sex-biased dispersal patterns.

Habitat Selection in a Changing Environment: The Relationship Between Habitat Alteration and Spotted Owl Territory Occupancy and Breeding Dispersal

Abstract Abstract. Understanding the effect of habitat alteration on avian behavior is important for understanding a species' ecology and ensuring its conservation. Therefore, we examined the relationship between Spotted Owl habitat selection and variation in habitat in the Sierra Nevada. We estimated habitat selection by modeling the probability of territory colonization (γ), territory extinction (ε), and breeding dispersal in relation to the amount of mature conifer forest within and among territories. Alteration of ≥20 ha of mature conifer forest (coniferous forest with >70% canopy cover dominated by medium [30.4–60.9 cm dbh] and large [>60.9 cm dbh] trees) within individual territories (n = 66) was negatively related to territory colonization and positively related to breeding dispersal probability. Although territory extinction was negatively related to the amount of mature conifer forest, it was not clear whether this relationship was due to variation of mature conifer forest within or among territories. Although modeling results for territory colonization and extinction generally supported the hypothesis that individuals are “ideal” when selecting a habitat in the sense that they settle in the highest-quality site available, we did not find a clear benefit in terms of habitat quality for Spotted Owls that exhibited breeding dispersal.

HABITAT SELECTION IN A CHANGING ENVIRONMENT: THE RELATIONSHIP BETWEEN HABITAT ALTERATION AND SPOTTED OWL TERRITORY OCCUPANCY AND BREEDING DISPERSAL

Abstract Abstract. Understanding the effect of habitat alteration on avian behavior is important for understanding a species' ecology and ensuring its conservation. Therefore, we examined the relationship between Spotted Owl habitat selection and variation in habitat in the Sierra Nevada. We estimated habitat selection by modeling the probability of territory colonization (γ), territory extinction (ϵ), and breeding dispersal in relation to the amount of mature conifer forest within and among territories. Alteration of ≥20 ha of mature conifer forest (coniferous forest with >70% canopy cover dominated by medium [30.4–60.9 cm dbh] and large [>60.9 cm dbh] trees) within individual territories (n = 66) was negatively related to territory colonization and positively related to breeding dispersal probability. Although territory extinction was negatively related to the amount of mature conifer forest, it was not clear whether this relationship was due to variation of mature conifer forest within or among terri...

Breeding Dispersal In the California Spotted Owl

Abstract Spotted Owls (Strix occidentalis) are territorial, generally nonmigratory, and strongly philopatric. Nevertheless, California Spotted Owls (S. o. occidentalis) exhibited breeding dispersal during 7% of interannual observations of banded individuals (n = 54 of 743 occasions). Based on ecological theory and published literature, we made a priori predictions about the factors associated with the probability of breeding dispersal and breeding dispersal distance, and about the consequences of dispersal. Breeding dispersal probability was higher for younger owls, single owls, paired owls that lost their mates, owls at lower quality sites, and owls that failed to reproduce in the year preceding dispersal. Sex had little effect on the probability of breeding dispersal. Dispersal distance was similar for female and male owls (median = 7 km, range = 1–33 km). We found no strong relationships between dispersal distance and any of the conditions that were associated with the probability of breeding dispersal. Dispersal resulted in improved territory quality in 72% of cases. These results indicate that breeding dispersal was condition-dependent and adaptive.

Breeding Dispersal In the California Spotted Owl

Abstract Spotted Owls (Strix occidentalis) are territorial, generally nonmigratory, and strongly philopatric. Nevertheless, California Spotted Owls (S. o. occidentalis) exhibited breeding dispersal during 7% of interannual observations of banded individuals (n = 54 of 743 occasions). Based on ecological theory and published literature, we made a priori predictions about the factors associated with the probability of breeding dispersal and breeding dispersal distance, and about the consequences of dispersal. Breeding dispersal probability was higher for younger owls, single owls, paired owls that lost their mates, owls at lower quality sites, and owls that failed to reproduce in the year preceding dispersal. Sex had little effect on the probability of breeding dispersal. Dispersal distance was similar for female and male owls (median = 7 km, range = 1–33 km). We found no strong relationships between dispersal distance and any of the conditions that were associated with the probability of breeding dispersal...

Sex‐biased survival and breeding dispersal probability in a patchy population of the Rock SparrowPetronia petronia

Demographic parameters of the polygynous Rock SparrowPetronia petroniawere investigated in a small patchy population in the Italian Alps. The population included two distinct breeding patches that differed in altitude and breeding success. Survival parameters were estimated by capture–recapture analysis of 170 individually marked animals. At the whole population level (Cormack–Jolly Seber model), no sex difference in local survival probability was detected. We then used a multisite capture–recapture approach (Arnason–Schwarz model) to investigate patch‐specific survival probability and between‐patch dispersal rate conditional on survival. Female local survival in the higher‐altitude patch (mean ± se: 0.54 ± 0.04) was significantly greater than in the other patch (0.37 ± 0.04), probably because permanent emigration from the study area was greater. In the higher‐altitude patch, breeding dispersal was constrained by the altitude limit and breeding movements were directed toward the patch at lower altitude. The probability of changing patch in the next breeding season was significantly higher for females (range 0.16–0.21) than for males (0.01–0.03). Breeding success varied between years and patches, being lower in the patch where frequency of polygamy and female local mortality were higher.