scholarly journals Fall supplemental feeding increases population growth rate of an endangered caribou herd

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10708
Author(s):  
Douglas C. Heard ◽  
Kathryn L. Zimmerman
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Population Growth Rate ◽  
Population Increase ◽  
Adult Survival ◽  
Management Approach ◽  
Annual Growth Rate ◽  
Supplemental Feeding ◽  
Management Actions ◽  
The Impact

Most woodland caribou (Rangifer tarandus caribou) populations are declining primarily because of unsustainable predation resulting from habitat-mediated apparent competition. Wolf (Canis lupus) reduction is an effective recovery option because it addresses the direct effect of predation. We considered the possibility that the indirect effects of predation might also affect caribou population dynamics by adversely affecting summer foraging behaviour. If spring and/or summer nutrition was inadequate, then supplemental feeding in fall might compensate for that limitation and contribute to population growth. Improved nutrition and therefore body condition going into winter could increase adult survival and lead to improved reproductive success the next spring. To test that hypothesis, we fed high-quality food pellets to free-ranging caribou in the Kennedy Siding caribou herd each fall for six years, starting in 2014, to see if population growth rate increased. Beginning in winter 2015–16, the Province of British Columbia began a concurrent annual program to promote caribou population increase by attempting to remove most wolves within the Kennedy Siding and the adjacent caribou herds’ ranges. To evaluate the impact of feeding, we compared lambdas before and after feeding began, and to the population trend in the adjacent Quintette herd over the subsequent four years. Supplemental feeding appeared to have an incremental effect on population growth. Population growth of the Kennedy Siding herd was higher in the year after feeding began (λ = 1.06) compared to previous years (λ = 0.91) and to the untreated Quintette herd (λ = 0.95). Average annual growth rate of the Kennedy Siding herd over the subsequent four years, where both feeding and wolf reduction occurred concurrently, was higher than in the Quintette herd where the only management action in those years was wolf reduction (λ = 1.16 vs. λ = 1.08). The higher growth rate of the Kennedy Siding herd was due to higher female survival (96.2%/yr vs. 88.9%/yr). Many caribou were in relatively poor condition in the fall. Consumption of supplemental food probably improved their nutritional status which ultimately led to population growth. Further feeding experiments on other caribou herds using an adaptive management approach would verify the effect of feeding as a population recovery tool. Our results support the recommendation that multiple management actions should be implemented to improve recovery prospects for caribou.

Effects of territorial status and life history on Sandhill Crane (Antigone canadensis) population dynamics in south-central Wisconsin, USA

2019 ◽  
Vol 97 (2) ◽  
pp. 112-120 ◽  
Author(s):  
Michael E. Wheeler ◽  
Jeb A. Barzen ◽  
Shawn M. Crimmins ◽  
Timothy R. Van Deelen
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Population Growth Rate ◽  
Demographic Data ◽  
Bird Species ◽  
Adult Survival ◽  
Vital Rates ◽  
Management Actions ◽  
South Central ◽  
Sandhill Cranes

Population growth rate in long-lived bird species is often most sensitive to changes in adult survival. Sandhill Cranes (Antigone canadensis (Linnaeus, 1758)) have long life spans, small broods, and delayed first reproduction. Only territorial adult Sandhill Cranes participate in breeding, and territory acquisition reflects the interplay between the availability of suitable territories and the variation in mortality of adult birds occupying those territories. We estimated vital rates of a population at equilibrium using long-term resightings data (2000–2014; n = 451 marked individuals) in a multistate mark–resight model and used a stage-structured projection matrix to assess how strongly territorial adult survival affects population growth rate. Elasticity analysis indicated territorial birds surviving and retaining territories had a 2.58 times greater impact on population growth compared with the next most important transition rate (survival of nonterritorial adults remaining nonterritorial). Knowing how changes in vital rates of various stage classes will differentially impact population growth rate allows for targeted management actions including encouraging growth in recovering populations, assessing opportunity for recreational harvest, or maintaining populations at a desired level. This study also highlights the value of collecting demographic data for all population segments, from which one can derive reproductive output or growth rate.

scholarly journals Breeding transients in capture–recapture modeling and their consequences for local population dynamics

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Daniel Oro ◽  
Daniel F. Doak
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Population Growth ◽  
Population Growth Rate ◽  
Local Population ◽  
Environmental Stochasticity ◽  
Adult Survival ◽  
Local Survival ◽  
First Reproduction ◽  
Capture Recapture

Abstract Standard procedures for capture–mark–recapture modelling (CMR) for the study of animal demography include running goodness-of-fit tests on a general starting model. A frequent reason for poor model fit is heterogeneity in local survival among individuals captured for the first time and those already captured or seen on previous occasions. This deviation is technically termed a transience effect. In specific cases, simple, uni-state CMR modeling showing transients may allow researchers to assess the role of these transients on population dynamics. Transient individuals nearly always have a lower local survival probability, which may appear for a number of reasons. In most cases, transients arise due to permanent dispersal, higher mortality, or a combination of both. In the case of higher mortality, transients may be symptomatic of a cost of first reproduction. A few studies working at large spatial scales actually show that transients more often correspond to survival costs of first reproduction rather than to permanent dispersal, bolstering the interpretation of transience as a measure of costs of reproduction, since initial detections are often associated with first breeding attempts. Regardless of their cause, the loss of transients from a local population should lower population growth rate. We review almost 1000 papers using CMR modeling and find that almost 40% of studies fitting the searching criteria (N = 115) detected transients. Nevertheless, few researchers have considered the ecological or evolutionary meaning of the transient phenomenon. Only three studies from the reviewed papers considered transients to be a cost of first reproduction. We also analyze a long-term individual monitoring dataset (1988–2012) on a long-lived bird to quantify transients, and we use a life table response experiment (LTRE) to measure the consequences of transients at a population level. As expected, population growth rate decreased when the environment became harsher while the proportion of transients increased. LTRE analysis showed that population growth can be substantially affected by changes in traits that are variable under environmental stochasticity and deterministic perturbations, such as recruitment, fecundity of experienced individuals, and transient probabilities. This occurred even though sensitivities and elasticities of these parameters were much lower than those for adult survival. The proportion of transients also increased with the strength of density-dependence. These results have implications for ecological and evolutionary studies and may stimulate other researchers to explore the ecological processes behind the occurrence of transients in capture–recapture studies. In population models, the inclusion of a specific state for transients may help to make more reliable predictions for endangered and harvested species.

Diagnosing declining grassland wader populations using simple matrix models

2009 ◽  
Vol 59 (1) ◽  
pp. 127-144 ◽  
Author(s):  
Lia Hemerik ◽  
Chris Klok ◽  
Maja Roodbergen
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Matrix Models ◽  
Population Growth Rate ◽  
Adult Stage ◽  
Demographic Data ◽  
Leslie Matrix ◽  
Adult Survival ◽  
Demographic Parameters ◽  
Survival And Reproduction

AbstractMany populations of wader species have shown a strong decline in number in Western-Europe in recent years. The use of simple population models such as matrix models can contribute to conserve these populations by identifying the most profitable management measures. Parameterization of such models is often hampered by the availability of demographic data (survival and reproduction). In particular, data on survival in the pre-adult (immature) stage of wader species that remain in wintering areas outside Europe are notoriously difficult to obtain, and are therefore virtually absent in the literature. To diagnose population decline in the wader species; Black-tailed Godwit, Curlew, Lapwing, Oystercatcher, and Redshank, we extended an existing modelling framework in which incomplete demographic data can be analysed, developed for species with a pre-adult stage of one year. The framework is based on a Leslie matrix model with three parameters: yearly reproduction (number of fledglings per pair), yearly pre-adult (immature) and yearly adult (mature) survival. The yearly population growth rate of these populations and the relative sensitivity of this rate to changes in survival and reproduction parameters (the elasticity) were calculated numerically and, if possible, analytically. The results showed a decrease in dependence on reproduction and an increase in pre-adult survival of the population growth rate with an increase in the duration of the pre-adult stage. In general, adult survival had the highest elasticity, but elasticity of pre-adult survival increased with time to first reproduction, a result not reported earlier. Model results showed that adult survival and reproduction estimates reported for populations of Redshank and Curlew were too low to maintain viable populations. Based on the elasticity patterns and the scope for increase in actual demographic parameters we inferred that conservation of the Redshank and both Curlew populations should focus on reproduction. For one Oystercatcher and the Black-tailed Godwit populations we suggested a focus on both reproduction and pre-adult survival. For the second Oystercatcher population pre-adult survival seemed the most promising target for conservation. And for the Lapwing populations all demographic parameters should be considered.

Population dynamics of an Egyptian desert shrub, Thymelaea hirsuta

1997 ◽  
Vol 75 (12) ◽  
pp. 2027-2037 ◽  
Author(s):  
Ali El-Keblawy ◽  
K. H. Shaltout ◽  
J. Lovett-Doust ◽  
A. Ramadan
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Population Growth Rate ◽  
Seedling Recruitment ◽  
Natural Populations ◽  
Plant Size ◽  
Population Variation ◽  
Adult Survival ◽  
Thymelaea Hirsuta ◽  
Egyptian Desert

Natural populations of the evergreen shrub, Thymelaea hirsuta (L.) Endl., were studied over 6 years at five desert habitats, in terms of seedling recruitment and adult survival and as a function of plant size and gender class. Habitat and time significantly influenced mortality of both reproductive and non-reproductive plants. Plant size also significantly affected adult mortality. Seedling recruitment varied significantly with habitat and year and approached zero some years. Significant among-year and among-population variation in population growth rates were observed over the 6 years of study, and all populations declined in size (ranging from −1.7% per year at the coastal dune site to −10.9% per year at the inland plateau site). Spearman rank correlation analysis between habitats ranked according to a north–south gradient and demographic variables indicates that this gradient is associated with a pattern of lower seedling emergence and survival and a lower population growth rate and greater mortality for all size-classes of Thymelaea plants. In experimental botanic garden plots, germination of seed collected from five natural populations, and seedling survival in the following year were assessed under conditions of high, medium, and low seedling density. Seedling emergency differed significantly according to maternal habitat. With regular watering, seeding survival to one year was 72% (averaged across habitats and densities). This compares with 64% for seedlings grown at the highest density, suggesting that the intense mortality observed under field conditions is more likely to be a result of water shortage than intraspecific competition. Key words: Egyptian desert, Thymelaea hirsuta, germination and establishment, seedlings, recruitment, competition, population growth rate.

A Cross-national Study of Environmental Performance and Culture: Implications of the Findings and Strategies

2019 ◽  
Vol 20 (4) ◽  
pp. 1051-1068 ◽  
Author(s):  
Sushant Kumar ◽  
Vishlavath Giridhar ◽  
Pradip Sadarangani
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Environmental Performance ◽  
Population Growth Rate ◽  
Practical Implication ◽  
Environmental Law ◽  
Cultural Dimensions ◽  
National Study ◽  
Per Capita ◽  
The Impact

The study investigates the impact of culture on environmental performance across 78 countries. The article explores the possible relationship with two datasets of international indices: (a) the six dimensional index of national culture proposed by Hofstede and (b) the environmental performance index (EPI) published by Yale Center for Environmental Law and Policy. It is widely established that population and economic development of a country play significant role in the improvement of environmental performance. In our study, we examine the impact of population growth rate and per-capita gross domestic product (GDP) on environmental performance using structure equation modelling. The results show that environmental performance is significantly influenced by the culture of the country. Per-capita GDP and population growth rate have a positive and negative relationships on the environmental performance. By measuring the cultural dimensions and their impact on global environmental performance, countries could identify the favouring cultural dimensions and design appropriate strategy to optimize the environmental performance. The article proposes the practical implication of results and strategies to improve environmental performance. The study is among the first in studying the cultural dynamics on environment and identify its favourable and adverse relationships for an optimum strategy.

scholarly journals VARIETY, COMPETITION, AND POPULATION IN ECONOMIC GROWTH: THEORY AND EMPIRICS

2019 ◽  
pp. 1-28
Author(s):  
Alberto Bucci ◽  
Lorenzo Carbonari ◽  
Giovanni Trovato
Keyword(s):  
Economic Growth ◽  
Growth Rate ◽  
Population Growth ◽  
Population Growth Rate ◽  
Population Change ◽  
Finite Mixture Model ◽  
Growth Theory ◽  
Long Run ◽  
Gdp Growth Rate ◽  
The Impact

We provide aggregate macroeconomic evidence on how, in the long run, a diverse degree of complexity in production may affect not only the rate of economic growth, but also the correlation between the latter, population growth and the monopolistic (intermediate) markups. For a sample of Organisation for Economic Co-operation and Development (OECD) countries, we find that the impact of population change on economic growth is slightly positive. According to our theoretical model, this implies that the losses due to more complexity in production are lower than the corresponding specialization gains. Using a finite mixture model, we also classify the countries in the sample and verify for each cluster the impact that the population growth rate and the intermediate sector’s markups exert on the 5-year average real gross domestic product (GDP) growth rate.

scholarly journals THE IMPACT OF HUMAN FACTORS ON THE CHANGE IN VEGETATION COVER OF THE BE RIVER BASIN IN THE PERIOD FROM 2000 TO 2015

2020 ◽  
Vol 15 (9) ◽  
pp. 53
Author(s):  
Phan Văn Trung ◽  
Nguyễn Thám
Keyword(s):  
Growth Rate ◽  
Human Factors ◽  
Population Growth ◽  
River Basin ◽  
Vegetation Cover ◽  
Population Growth Rate ◽  
Mapping Method ◽  
Rapid Urbanization ◽  
Set Up ◽  
The Impact

 The Be river basin is located in the area with a rapid urbanization rate and a large immigrants proportion annually. Therefore, the population growth rate for the period from 2000 to 2015 in the river basin is up 3,53% which is 3,27 times as high as the population growth rate of Vietnam. These are the major causes leading to the fluctuation in vegetation cover of the Be river basin during over time. This research used methodologies including data collection, statistical analysis, mapping method and geographic information system to evaluate the impact of human factors to the vegetation cover fluctuation of the Be river basin in the period from 2000 to 2015. Based on the results of change map in the vegetation cover, a research group set up fluctuating matrix, analyze to clarify the vegetation coverfluctuation situation due to human’s impacts in the Be river basin in the period from 2000 to 2015. 

scholarly journals Education and the Challenge of Poverty Alleviation in Nigeria

2020 ◽  
pp. 12-23
Author(s):  
R. Oke ◽  
S. I. Oladeji ◽  
O. P. Olofin
Keyword(s):  
Economic Growth ◽  
Growth Rate ◽  
Population Growth ◽  
Educational System ◽  
Population Growth Rate ◽  
Interactive Effect ◽  
Physical Capital ◽  
Employment Rate ◽  
Poverty Level ◽  
The Impact

Using Vector Autoregressive and Autoregressive Distributed Lag methods to examine the impact of education on poverty level and the interactive effect of education and economic growth on poverty level in Nigeria between 1985 and 2016, our results show that education promotes poverty level, instead of reducing it. We found significant cointegrating relationship among poverty, economic growth, education, employment rate, population growth rate, real physical capital formation, education level and real GDP. In the short-run, employment rate reduces poverty level, population growth rate increases poverty level both in the short and long-run. The results of interactive effect of economic growth and education on poverty growth show that jointly economic growth and education reduce poverty, although the results are not statistically significant. This shows that they have minimal impact on poverty level in Nigeria. Our findings may not be surprising, given the current slow-down in Nigeria educational system and the wide gap between the few rich and the larger poor. The study suggests improvement in Nigeria educational system so as promote employment and curb rising poverty level.

scholarly journals Delayed maturity does not offset negative impact afflicted by ectoparasitism in salmon

2021 ◽  
Author(s):  
Knut Wiik Vollset ◽  
Martin Krkosek
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Body Size ◽  
Population Growth ◽  
Population Growth Rate ◽  
Negative Impact ◽  
Host Population ◽  
Sea Lice ◽  
Fish Farms ◽  
The Impact

AbstractThe negative effects of parasitism on host population dynamics may be mediated by plastic compensatory life-history changes in hosts. Theory predicts that hosts should shift their life-history towards early reproduction in response to virulent pathogens to maximize reproduction before death. However, for sublethal infections that affect growth, hosts whose fecundity is correlated with body size are predicted to shift towards delayed reproduction associated with larger body size and higher fecundity. This has been observed in Atlantic salmon and parasitic sea lice, via mark-recapture studies that recover mature fish from paired groups of control and parasiticide-treated smolts. We investigated whether such louse-induced changes to age at maturity can offset some of the negative effect of mortality on population growth rate in salmon using a structured population matrix model. Model results show that delayed maturity can partially compensate for reduced survival. However, this only occurs when marine survival is moderate to poor and growth conditions at sea are good. Also, the impact of delayed maturity on population growth when parameterizing the model with empirical data is negligible compared with effects of direct mortality. Our model thus suggests that management that works on minimizing the effect of sea lice from fish farms on wild salmon should focus mainly on correctly quantifying the effect of parasite-induced mortality during the smolt stage if the goal is to maximize population growth rate.

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