scholarly journals Assessing the Viability of the Sarasota Bay Community of Bottlenose Dolphins

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.

scholarly journals Range expansion is associated with increased survival and fecundity in a long-lived bat species

2019 ◽  
Vol 286 (1906) ◽  
pp. 20190384 ◽  
Author(s):  
P.-L. Jan ◽  
L. Lehnen ◽  
A.-L. Besnard ◽  
G. Kerth ◽  
M. Biedermann ◽  
...  
Keyword(s):  
Life History ◽  
Population Growth ◽  
Range Expansion ◽  
Empirical Studies ◽  
Simulated Data ◽  
Adult Survival ◽  
Juvenile Survival ◽  
Average Growth ◽  
Population Growth Rates ◽  
Expanding Population

The speed and dynamics of range expansions shape species distributions and community composition. Despite the critical impact of population growth rates for range expansion, they are neglected in existing empirical studies, which focus on the investigation of selected life-history traits. Here, we present an approach based on non-invasive genetic capture–mark–recapture data for the estimation of adult survival, fecundity and juvenile survival, which determine population growth. We demonstrate the reliability of our method with simulated data, and use it to investigate life-history changes associated with range expansion in 35 colonies of the bat species Rhinolophus hipposideros . Comparing the demographic parameters inferred for 19 of those colonies which belong to an expanding population with those inferred for the remaining 16 colonies from a non-expanding population reveals that range expansion is associated with higher net reproduction. Juvenile survival was the main driver of the observed reproduction increase in this long-lived bat species with low per capita annual reproductive output. The higher average growth rate in the expanding population was not associated with a trade-off between increased reproduction and survival, suggesting that the observed increase in reproduction stems from a higher resource acquisition in the expanding population. Environmental conditions in the novel habitat hence seem to have an important influence on range expansion dynamics, and warrant further investigation for the management of range expansion in both native and invasive species.

scholarly journals Spatial variation in giraffe demography: a test of 2 paradigms

2016 ◽  
Vol 97 (4) ◽  
pp. 1015-1025 ◽  
Author(s):  
Derek E. Lee ◽  
Monica L. Bond ◽  
Bernard M. Kissui ◽  
Yustina A. Kiwango ◽  
Douglas T. Bolger
Keyword(s):  
Population Growth ◽  
Spatial Variation ◽  
Adult Female ◽  
Vital Rate ◽  
Adult Survival ◽  
Continental Scale ◽  
Demographic Rates ◽  
Adult Females ◽  
Calf Survival ◽  
Female Survival

Abstract Examination of spatial variation in demography among or within populations of the same species is a topic of growing interest in ecology. We examined whether spatial variation in demography of a tropical megaherbivore followed the “temporal paradigm” or the “adult survival paradigm” of ungulate population dynamics formulated from temperate-zone studies. We quantified spatial variation in demographic rates for giraffes (Giraffa camelopardalis) at regional and continental scales. Regionally, we used photographic capture-mark-recapture data from 860 adult females and 449 calves to estimate adult female survival, calf survival, and reproduction at 5 sites in the Tarangire ecosystem of Tanzania. We examined potential mechanisms for spatial variation in regional demographic rates. At the continental scale, we synthesized demographic estimates from published studies across the range of the species. We created matrix population models for all sites at both scales and used prospective and retrospective analyses to determine which vital rate was most important to variation in population growth rate. Spatial variability of demographic parameters at the continental scale was in agreement with the temporal paradigm of low variability in adult survival and more highly variable reproduction and calf survival. In contrast, at the regional scale, adult female survival had higher spatial variation, in agreement with the adult survival paradigm. At both scales, variation in adult female survival made the greatest contribution to variation in local population growth rates. Our work documented contrasting patterns of spatial variation in demographic rates of giraffes at 2 spatial scales, but at both scales, we found the same vital rate was most important. We also found anthropogenic impacts on adult females are the most likely mechanism of regional population trajectories.

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

Oryx ◽  
2015 ◽  
Vol 50 (4) ◽  
pp. 583-592 ◽  
Author(s):  
Kate Ashbrook ◽  
Andrew Taylor ◽  
Louise Jane ◽  
Ian Carter ◽  
Tamás Székely
Keyword(s):  
Habitat Management ◽  
Bird Species ◽  
Population Viability ◽  
Adult Survival ◽  
Wild Populations ◽  
Great Bustard ◽  
Otis Tarda ◽  
Demographic Rates ◽  
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.

The Railways, Urbanization, and Local Demography in England and Wales, 1825–1911

2010 ◽  
Vol 34 (2) ◽  
pp. 199-228
Author(s):  
Ian N. Gregory ◽  
Jordi Martí Henneberg
Keyword(s):  
World War I ◽  
Population Growth ◽  
World War ◽  
England And Wales ◽  
Rail Network ◽  
Level Data ◽  
Integrate Data ◽  
Single Set ◽  
Over Time

This article uses geographic information systems (GIS) to explore the growth of the rail network in England and Wales in the period before World War I. It uses two major GIS databases, one containing data on the growth of the rail network, including both lines and stations, and one containing parish-level populations. The parish-level data are particularly important for two reasons: they give an unparalleled level of spatial detail, and they are interpolated onto a single set of boundaries over time, which allows direct long-term comparisons. GIS's ability to integrate data allows the article to shed new light on how quickly the railways spread into the country's population. It then explores whether gaining a station made it more likely for a parish's population growth to increase and whether gaining one early was an advantage compared to gaining one relatively late. The article explores this impact at a variety of urban levels.

Use of Pup Counts in Indexing Population Changes in Pinnipeds

1985 ◽  
Vol 42 (5) ◽  
pp. 873-879 ◽  
Author(s):  
J. M. Berkson ◽  
D. P. DeMaster
Keyword(s):  
Life History ◽  
Population Growth ◽  
Maximum Rate ◽  
Population Change ◽  
Adult Survival ◽  
Population Changes ◽  
Feedback Mechanisms ◽  
Density Dependent ◽  
Life History Parameters ◽  
Pup Survival

A series of population simulations were used to test the accuracy of estimating the discrete rates of population change (RPC) from annual pup counts. The simulations indicate that pup counts can give a biased estimate of RPC, and that the magnitude and direction of bias depends on which life history parameters are density dependent and on the maximum rate of population change. In general, if pre-census pup survival is density dependent the estimated RPC using pup counts is too low. If post-census pup survival is density dependent, the estimated RPC is too high. If adult survival is density dependent, there is very little bias in the estimate. The results indicate that pup counts can be reliable indicators of population growth, but caution should be used in interpreting the results unless density feedback mechanisms have been identified.

scholarly journals Long-term changes in the breeding biology of a New Zealand bellbird population suggest plasticity in life-history responses to ecological restoration

2021 ◽  
Author(s):  
Michelle M. Roper ◽  
M.T. Harmer Aaron ◽  
Dianne H Brunton
Keyword(s):  
Life History ◽  
New Zealand ◽  
Reproductive Success ◽  
Ecological Restoration ◽  
Breeding Biology ◽  
Life History Strategies ◽  
Local Conditions ◽  
Anthornis Melanura ◽  
Over Time

AbstractEcological restoration projects provide excellent opportunities to study how animals adapt their life-history strategies in response to changeable environments. A fundamental way animals can optimise reproductive success in changing conditions is trading-off aspects of their breeding system. The New Zealand bellbird (Anthornis melanura) has had a long-term presence on the small restoration island, Tiritiri Matangi Island (Tiri), spanning the island’s degraded agricultural past to its current extensively restored state. We studied the breeding biology of this bellbird population to assess how their reproductive life-history strategies have responded over time to the restoration on Tiri. We compared the current breeding data (2012–2016) of the bellbirds with data from between 2001–2010 (including Baillie, 2011, Cope, 2007), and from 1977–1978 (Anderson and Craig, 2003), prior to the island’s restoration. We also explored associations between abiotic/biotic factors and bellbird reproductive success for the most recent period (2012–2016). Our main finding was that clutch size significantly declined over time from a mean of 3.6 to 2.4 eggs per nest and this decline correlated with increasing population density. This is consistent with a density dependent effect, although further data are required to empirically test this conclusion. Overall, the earliest spring laying dates were in late August and the latest extended to January, with all chicks fledged by the end of February. Nest success was 47% (range 40 – 54%) across 2012–2016, falling within a similar range as previous studies. We found little effect of year, weather, parental age or morphometrics on reproductive success. We observed directional change in patterns of parental investment between 1977–1978 and 2012–2016; in 2012–2016, parents persisted with raising single broods rather than abandoning and re-nesting to raise larger broods. These results suggest that the bellbirds’ life-history traits are plastic in response to local conditions which provides an advantage when repopulating a regenerating or changing habitat.

Population Demography

2021 ◽  
pp. 34-51
Author(s):  
J Patrick Vaughan ◽  
Cesar Victora ◽  
A Mushtaque R Chowdhury
Keyword(s):  
Life Expectancy ◽  
Population Growth ◽  
Population Data ◽  
Sex Structure ◽  
Demographic Rates ◽  
Population Information ◽  
Epidemiological Transitions ◽  
Over Time ◽  
Age And Sex

This chapter reviews population measurements and the demographic and epidemiological transitions and how these may change over time. Knowledge of the population age and sex structure and distribution are essential to estimate those people at most risk and for estimating population access to services and programmes. Sources of population information are presented and factors highlighted for the quality of population data. Definitions of demographic rates and life expectancy, population growth, census procedures, death certification, and demographic surveillance are all outlined.

scholarly journals The Disconnect Between Short- and Long-Term Population Projections for Plant Reintroductions

2022 ◽  
Vol 2 ◽  
Author(s):  
Lalasia Bialic-Murphy ◽  
Tiffany M. Knight ◽  
Kapua Kawelo ◽  
Orou G. Gaoue
Keyword(s):  
Population Growth ◽  
Population Projections ◽  
Population Growth Rates ◽  
Population Extinction ◽  
Management Actions ◽  
Natural Seedling ◽  
Short And Long Term ◽  
Plant Reintroductions ◽  
Over Time

The reintroduction of rare species in natural preserves is a commonly used restoration strategy to prevent species extinction. An essential first step in planning successful reintroductions is identifying which life stages (e.g., seeds or large adults) should be used to establish these new populations. Following this initial establishment phase, it is necessary to determine the level of survival, growth, and recruitment needed to maintain population persistence over time and identify management actions that will achieve these goals. In this 5-year study, we projected the short- and long-term population growth rates of a critically endangered long-lived shrub, Delissea waianaeensis. Using this model system, we show that reintroductions established with mature individuals have the lowest probability of quasi-population extinction (10 individuals) and the highest increase in population abundance. However, our results also demonstrate that short-term increases in population abundances are overly optimistic of long-term outcomes. Using long-term stochastic model simulations, we identified the level of natural seedling regeneration needed to maintain a positive population growth rate over time. These findings are relevant for planning future reintroduction efforts for long-lived species and illustrate the need to forecast short- and long-term population responses when evaluating restoration success.

scholarly journals Long-term urban carbon dioxide observations reveal spatial and temporal dynamics related to urban characteristics and growth

2018 ◽  
Vol 115 (12) ◽  
pp. 2912-2917 ◽  
Author(s):  
Logan E. Mitchell ◽  
John C. Lin ◽  
David R. Bowling ◽  
Diane E. Pataki ◽  
Courtenay Strong ◽  
...  
Keyword(s):  
Population Growth ◽  
Rural Areas ◽  
Temporal Dynamics ◽  
Salt Lake ◽  
Nonlinear Relationship ◽  
Emission Inventories ◽  
Urban Core ◽  
Decadal Scale ◽  
Over Time

Cities are concentrated areas of CO2 emissions and have become the foci of policies for mitigation actions. However, atmospheric measurement networks suitable for evaluating urban emissions over time are scarce. Here we present a unique long-term (decadal) record of CO2 mole fractions from five sites across Utah’s metropolitan Salt Lake Valley. We examine “excess” CO2 above background conditions resulting from local emissions and meteorological conditions. We ascribe CO2 trends to changes in emissions, since we did not find long-term trends in atmospheric mixing proxies. Three contrasting CO2 trends emerged across urban types: negative trends at a residential-industrial site, positive trends at a site surrounded by rapid suburban growth, and relatively constant CO2 over time at multiple sites in the established, residential, and commercial urban core. Analysis of population within the atmospheric footprints of the different sites reveals approximately equal increases in population influencing the observed CO2, implying a nonlinear relationship with CO2 emissions: Population growth in rural areas that experienced suburban development was associated with increasing emissions while population growth in the developed urban core was associated with stable emissions. Four state-of-the-art global-scale emission inventories also have a nonlinear relationship with population density across the city; however, in contrast to our observations, they all have nearly constant emissions over time. Our results indicate that decadal scale changes in urban CO2 emissions are detectable through monitoring networks and constitute a valuable approach to evaluate emission inventories and studies of urban carbon cycles.

scholarly journals Population Trends and Urbanization: Simulating Density Effects Using a Local Regression Approach

2020 ◽  
Vol 9 (7) ◽  
pp. 454 ◽  
Author(s):  
Gloria Polinesi ◽  
Maria Cristina Recchioni ◽  
Rosario Turco ◽  
Luca Salvati ◽  
Kostas Rontos ◽  
...  
Keyword(s):  
Population Density ◽  
Population Growth ◽  
Growth Rates ◽  
European Regions ◽  
Density Dependent ◽  
Metropolitan Growth ◽  
Dependent Processes ◽  
Demographic Growth ◽  
Over Time

Density-dependent population growth regulates long-term urban expansion and shapes distinctive socioeconomic trends. Despite a marked heterogeneity in the spatial distribution of the resident population, Mediterranean European countries are considered more homogeneous than countries in other European regions as far as settlement structure and processes of metropolitan growth are concerned. However, rising socioeconomic inequalities among Southern European regions reflect latent demographic and territorial transformations that require further investigation. An integrated assessment of the spatio-temporal distribution of resident populations in more than 1000 municipalities (1961–2011) was carried out in this study to characterize density-dependent processes of metropolitan growth in Greece. Using geographically weighted regressions, the results of our study identified distinctive local relationships between population density and growth rates over time. Our results demonstrate that demographic growth rates were non-linearly correlated with other variables, such as population density, with positive and negative impacts during the first (1961–1971) and the last (2001–2011) observation decade, respectively. These findings outline a progressive shift over time from density-dependent processes of population growth, reflecting a rapid development of large metropolitan regions (Athens, Thessaloniki) in the 1960s, to density-dependent processes more evident in medium-sized cities and accessible rural regions in the 2000s. Density-independent processes of population growth have been detected in the intermediate study period (1971–2001). This work finally discusses how a long-term analysis of demographic growth, testing for density-dependent mechanisms, may clarify the intrinsic role of population concentration and dispersion in different phases of the metropolitan cycle in Mediterranean Europe.

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