Impacts of survival and reproductive success on the long-term population viability of reintroduced great bustards Otis tarda in the UK

AbstractReintroductions aim to re-establish species within their historical ranges through the release of wild- or captive-bred individuals following extirpation (or extinction) in the wild. There is no general agreement on what constitutes a successful reintroduction but the probability of the population achieving long-term persistence should be addressed. Here we review a 10-year trial reintroduction of the great bustard Otis tarda, a globally threatened bird species, to the UK and assess the long-term population viability. Despite changes in rearing and release strategy, initial post-release survival probability remained consistently low, with only 11.3% of bustards (n = 167) surviving from release to 1 year post-release. Nineteen breeding attempts were made by eight females; however, only one chick survived > 100 days after hatching, and no wild juveniles have recruited into the population. Using demographic rates from the UK population and wild populations elsewhere, and stochastic population modelling, we investigate the viability of this reintroduced population by predicting population size over the next 10 years. Under current demographic rates the population was predicted to decline rapidly. Self-sufficiency was predicted only using the highest estimates from the UK population for first-year and adult survival, and recruitment rates from wild populations elsewhere. Although changes have been made in rearing, release strategies, habitat management and release sites used, these changes appear to have a modest effect on long-term viability. Substantial improvements in survival rates and productivity are necessary to establish a viable great bustard population in the UK, and we consider this unlikely.

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The UK great bustard Otis tarda reintroduction trial: a 5-year progress report

Oryx ◽

10.1017/s0030605311000627 ◽

2011 ◽

Vol 46 (1) ◽

pp. 112-121 ◽

Cited By ~ 13

Author(s):

Robert J. Burnside ◽

Ian Carter ◽

Alasdair Dawes ◽

David Waters ◽

Leigh Lock ◽

...

Keyword(s):

Release Site ◽

Progress Report ◽

Adult Survival ◽

First Year ◽

Founder Population ◽

Trial Period ◽

Great Bustard ◽

Otis Tarda ◽

The Uk ◽

The 19Th Century

AbstractThe great bustard Otis tarda became extinct in the UK during the 19th century due to a combination of factors, including hunting, egg collection and changes in agriculture. In 2003 a 10-year licence was granted to begin a trial to reintroduce the species back to the UK. Here we report on the first 5 years of the trial and assess the progress made towards establishing a founder population. From April 2004 to September 2009 a total of 102 great bustard chicks were imported from Russia and 86 released on Salisbury Plain. Monitoring showed that post-release survival was 18% in the first year following release, and that mortality of released bustards was mainly attributable to predation and collisions. Estimated adult survival was 74%, although the sample size was small. All known surviving great bustards are faithful to the surroundings of the release site, returning throughout the year. A lek has been established where males have been observed displaying to females. The first nesting attempt was in 2007, and in 2009 two females aged 3 and 4 years successfully nested, fledging one chick each. Models incorporating the new demographic estimates suggest that at the end of the 10-year trial period the project can expect to have 8–26 adults as a founder population.

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Evaluating release alternatives for a long-lived bird species under uncertainty about long-term demographic rates

Journal of Ornithology ◽

10.1007/s10336-010-0592-y ◽

2010 ◽

Vol 152 (S2) ◽

pp. 339-353 ◽

Cited By ~ 27

Author(s):

Clinton T. Moore ◽

Sarah J. Converse ◽

Martin J. Folk ◽

Michael C. Runge ◽

Stephen A. Nesbitt

Keyword(s):

Bird Species ◽

Demographic Rates

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Factors causing long-term dynamics in the abundance of the Trans-Volga Great bustard (Otis tarda L.) population

Biology Bulletin ◽

10.1134/s1062359013100063 ◽

2013 ◽

Vol 40 (10) ◽

pp. 843-853 ◽

Cited By ~ 3

Author(s):

M. L. Oparin ◽

O. S. Oparina ◽

I. A. Kondratenkov ◽

A. B. Mamaev ◽

V. V. Piskunov

Keyword(s):

Great Bustard ◽

Otis Tarda

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Population Viability and Resource Competition on North Brother Island: Conservation Implications for Tuatara (Sphenodon Punctatus) and Duvaucel's Gecko (Hoplodactylus Duvaucelii)

10.26686/wgtn.16972315.v1 ◽

2021 ◽

Author(s):

◽

Joanna Wilson

Keyword(s):

Sex Ratio ◽

Population Size ◽

Body Condition ◽

Resource Competition ◽

Adult Population ◽

Population Viability ◽

Adult Survival ◽

Intraspecific Interactions ◽

Sphenodon Punctatus

<p>Population viability for small, isolated populations is determined by many factors, particularly demographic stochasticity. Coexistence of communities is promoted through resource partitioning, particularly if species share similar niche requirements. Demographic characteristics, long-term trends and patterns of partitioning were investigated for two reptile species: tuatara (Sphenodon punctatus) and Duvaucel's gecko (Hoplodactylus duvaucelii), using mark recapture techniques on North Brother Island, New Zealand. Capture time and location were recorded as well as snout-vent length, mass and sex of individuals. Adult population size, sex ratio, survival and recapture probability for both species were estimated. Intervention will be needed to prevent population collapse for tuatara, as the population is male-biased (3.24 males: 1 female), with sub-adults exhibiting a stronger bias (4.1 males: 1 female). The total population size is estimated at 390-437 adults, with high adult survival (95%). The Duvaucel's gecko population is stable enough to be harvested for translocation, as the population was estimated at 583-677 adults, with an even sex ratio. Adult survival was high (92%) and longevity is at least 43-50 years. Patterns in partitioning suggest tuatara are excluding Duvaucel's gecko as tuatara occupy vegetated areas and few animals were caught at the same time in the same place as a member of the other species (~10%). Long-term site fidelity appears to occur in both species as the majority of animals were captured previously within 10m (tuatara) or 15m (Duvaucel's gecko) of their 2008 location, and travelled less than 2m per year on average. Tuatara show an overall decline in body condition since 1957, which is more rapid in females, and may be related to intraspecific interactions and density-dependent effects. Gecko body condition is not declining, suggesting no negative effects at the population level are occurring as a result of competitive exclusion. This study indicates that characteristics that have implications for population viability have the capacity to differ, even for species with similar niche requirements occupying the same habitat, and supports the considerable value of long-term monitoring.</p>

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Assessing the Viability of the Sarasota Bay Community of Bottlenose Dolphins

Frontiers in Marine Science ◽

10.3389/fmars.2021.788086 ◽

2021 ◽

Vol 8 ◽

Author(s):

Robert C. Lacy ◽

Randall S. Wells ◽

Michael D. Scott ◽

Jason B. Allen ◽

Aaron A. Barleycorn ◽

...

Keyword(s):

Life History ◽

Population Growth ◽

Adult Survival ◽

Model Parameters ◽

Catastrophic Events ◽

Demographic Rates ◽

Sarasota Bay ◽

Population Demographic ◽

Over Time

Population models, such as those used for Population Viability Analysis (PVA), are valuable for projecting trends, assessing threats, guiding environmental resource management, and planning species conservation measures. However, rarely are the needed data on all aspects of the life history available for cetacean species, because they are long-lived and difficult to study in their aquatic habitats. We present a detailed assessment of population dynamics for the long-term resident Sarasota Bay common bottlenose dolphin (Tursiops truncatus) community. Model parameters were estimated from 27 years of nearly complete monitoring, allowing calculation of age-specific and sex-specific mortality and reproductive rates, uncertainty in parameter values, fluctuation in demographic rates over time, and intrinsic uncertainty in the population trajectory resulting from stochastic processes. Using the Vortex PVA model, we projected mean population growth and quantified causes of variation and uncertainty in growth. The ability of the model to simulate the dynamics of the population was confirmed by comparing model projections to observed census trends from 1993 to 2020. When the simulation treated all losses as deaths and included observed immigration, the model projects a long-term mean annual population growth of 2.1%. Variance in annual growth across years of the simulation (SD = 3.1%) was due more to environmental variation and intrinsic demographic stochasticity than to uncertainty in estimates of mean demographic rates. Population growth was most sensitive to uncertainty and annual variation in reproduction of peak breeding age females and in calf and juvenile mortality, while adult survival varied little over time. We examined potential threats to the population, including increased anthropogenic mortality and impacts of red tides, and tested resilience to catastrophic events. Due to its life history characteristics, the population was projected to be demographically stable at smaller sizes than commonly assumed for Minimum Viable Population of mammals, but it is expected to recover only slowly from any catastrophic events, such as disease outbreaks and spills of oil or other toxins. The analyses indicate that well-studied populations of small cetaceans might typically experience slower growth rates (about 2%) than has been assumed in calculations of Potential Biological Removal used by management agencies to determine limits to incidental take of marine mammals. The loss of an additional one dolphin per year was found to cause significant harm to this population of about 150 to 175 animals. Beyond the significance for the specific population, demographic analyses of the Sarasota Bay dolphins provide a template for examining viability of other populations of small cetaceans.

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Opposing population trajectories in two Bustard species: A long-term study in a protected area in Central Spain

Bird Conservation International ◽

10.1017/s0959270918000254 ◽

2018 ◽

Vol 29 (2) ◽

pp. 308-320 ◽

Cited By ~ 3

Author(s):

FABIÁN CASAS ◽

FRANÇOIS MOUGEOT ◽

BEATRIZ ARROYO ◽

MANUEL B. MORALES ◽

ISRAEL HERVÁS ◽

...

Keyword(s):

Protected Area ◽

Bird Species ◽

Population Monitoring ◽

Population Trends ◽

Central Spain ◽

Great Bustard ◽

Long Term Study ◽

Tetrax Tetrax ◽

Steppe Birds

SummaryIn conservation biology, population monitoring is a critical step, particularly for endangered groups, such as steppe birds in European agro-ecosystems. Long-term population monitoring allows for determination of species population trends and also provides insights into the relative roles that environmental variability and human activities have on priority species. Here, we compare the population trends of two sympatric, closely related farmland bird species, the Little Bustard Tetrax tetrax and Great Bustard Otis tarda, in a protected area of Central Spain, which is their main stronghold in Europe. Over 12 years of monitoring, the abundance of Little and Great Bustards shifted in opposite directions in our study area. Little Bustard abundance decreased significantly (both males [-56%], and harder-to-detect females [-55%]), while Great Bustard abundance increased significantly (1,800%). Future surveys should be more precise and frequent for Little Bustards to facilitate evaluation of their population status and trends. We recommend annual surveys in 2–3 important locations by region throughout the breeding range for Little Bustards, while for Great Bustard the current regional monitoring programmes would be sufficient.

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Effects of power lines on flight behaviour of the West-Pannonian Great Bustard Otis tarda population

Bird Conservation International ◽

10.1017/s0959270910000432 ◽

2010 ◽

Vol 21 (2) ◽

pp. 142-155 ◽

Cited By ~ 9

Author(s):

RAINER RAAB ◽

PÉTER SPAKOVSZKY ◽

EIKE JULIUS ◽

CLAUDIA SCHÜTZ ◽

CHRISTIAN H. SCHULZE

Keyword(s):

Random Distribution ◽

Bird Species ◽

Power Lines ◽

Great Bustard ◽

Flight Behaviour ◽

Otis Tarda ◽

Flight Direction ◽

Eastern Austria ◽

The Mean ◽

Mean Vector

SummaryFlight directions of Great Bustards Otis tarda after take-off were used to analyse effects of power lines on spatial movements of this highly endangered bird species. Data on flight directions came from Great Bustard observations conducted in eastern Austria (northern and eastern parts of Lower Austria, northern part of Burgenland), western Slovakia and western Hungary. Flight directions were determined by a constructed line connecting take-off site and the bird’s position after a flown distance of 100 m. Up to a distance of 800 m from the nearest power line, mean flight direction of Great Bustards after take-off deviated significantly from a random distribution. The mean flight direction angles clearly indicate that take-off flight routes point away from power lines at an angle of approximately 180°. Furthermore, flight directions of bustards still deviated from a random distribution in two 200-m distance bands much further away from power lines (> 1,200–1,400 m, > 1,400–1,600 m), possibly suggesting that even at larger distances from power lines flight directions might still be affected by such artificial linear landscape structures. With increasing distance to nearest power lines, mean vector length r values of flight paths decrease significantly, while circular standard deviations S values increase significantly. Very similar results were achieved independently if all data were pooled or analysed separately for individual study areas for which the number of flight observations was large enough to conduct reliable analyses. Our study reports a strong effect of power lines on the flight behaviour of Great Bustards, at least up to a distance of 800 m, perhaps even up to 1,600 m. Although this may significantly reduce the risk of collision with power lines it most likely has severe consequences for the spatial movements of birds within the entire landscape and between potentially suitable breeding and foraging habitats.

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Variable effects of a changing climate on lay dates and productivity across the range of the Red-cockaded Woodpecker

The Condor ◽

10.1093/condor/duz048 ◽

2019 ◽

Author(s):

Stephanie M DeMay ◽

Jeffrey R Walters

Keyword(s):

Habitat Management ◽

Bird Species ◽

Local Conditions ◽

Climate Conditions ◽

Changing Climate ◽

Spring Temperatures ◽

Red Cockaded Woodpecker ◽

Pinus Spp ◽

Over Time

Abstract Many temperate bird species are breeding earlier in response to warming temperatures. We examined the effects of climate on breeding phenology and productivity in 19 populations across the range of the Red-cockaded Woodpecker (Dryobates borealis), an endangered species endemic to pine (Pinus spp.) forests in the southeastern United States. Red-cockaded Woodpeckers nested earlier in warmer springs and delayed nesting in wetter springs. Earlier nesting and larger group sizes resulted in higher productivity. Spring temperatures have warmed over time across the range, but this has not led to range-wide advances in nesting date over time. Coastal and northern populations have exhibited a trend of earlier nesting over time, but the response of inland populations has been variable, including some populations in which nesting has become later over time. Geographic patterns included high and increasing productivity at higher latitudes, and declining productivity in the southwestern portion of the range, suggesting a possible shift in acceptable climate conditions for the species. Earlier nesting over time was associated with increasing productivity at higher latitudes, while elsewhere earlier nesting over time was associated with declining or stable productivity, suggesting that populations differ in their ability to adjust to a changing climate. The Red-cockaded Woodpecker is a habitat specialist heavily reliant on habitat management and has little capacity to shift its range, so its long-term viability will depend on its ability to adjust in place to changing local conditions.

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Human disturbance and conspecifics influence display site selection by Great Bustards Otis tarda

Bird Conservation International ◽

10.1017/s0959270913000142 ◽

2013 ◽

Vol 24 (1) ◽

pp. 32-44 ◽

Cited By ~ 5

Author(s):

ROBERT J. BURNSIDE ◽

ZSOLT VÉGVÁRI ◽

RICHARD JAMES ◽

SANDOR KONYHÁS ◽

GÁBOR KOVÁCS ◽

...

Keyword(s):

Habitat Selection ◽

Habitat Quality ◽

Site Selection ◽

Human Disturbance ◽

Habitat Management ◽

Habitat Choice ◽

Social Cues ◽

Great Bustard ◽

Otis Tarda ◽

Social Species

SummaryUnderstanding habitat selection and assessing habitat quality have an important role in habitat management and prioritisation of areas for protection. However, interpretations of habitat selection and habitat quality can be confounded by social effects such as conspecific attraction. Using 7 years’ data from a well monitored Great Bustard Otis tarda population in Central Europe, we investigated the roles of human disturbance and social cues in display site selection of male Great Bustards Otis tarda. The spatial distribution of displaying males was best predicted by human disturbance. In addition, the number of males attending display sites was strongly correlated to the number of females present and not with disturbance. This suggests that abundance could be a misleading metric for habitat quality in social species. Our results highlight the roles of disturbance and social cues in male habitat choice, and suggest that social factors need to be taken into consideration for management of endangered populations.

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