Seasonal rainfall in subtropical montane cloud forests drives demographic fluctuations in a Green-backed Tit population

The Condor ◽  
2020 ◽  
Author(s):  
Ming-Tang Shiao ◽  
Mei-Chen Chuang ◽  
Hsiao-Wei Yuan ◽  
Ying Wang
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Cloud Forest ◽  
Geometric Mean ◽  
Local Population ◽  
Simulated Data ◽  
Seasonal Rainfall ◽  
Adult Survival ◽  
Adult Bird ◽  
Long Term Study

Abstract Montane birds are vulnerable to climate change. However, the mechanisms by which weather drives demographic processes in montane birds have seldom been investigated. We conducted a long-term study (2009–2019) on the Green-backed Tit (Parus monticolus), an insectivorous passerine, in the montane cloud forest of subtropical Taiwan. We explored the effects of weather variability on the productivity and survival of adult Green-backed Tits. Nest survival was negatively associated with seasonal rainfall during the breeding season (April–July) and was lower in early clutches than in late clutches. Higher typhoon-induced precipitation during the postbreeding period (July–September) was related to reduced adult survival, but neither summer temperature nor winter weather conditions were found to be related to adult bird survival. We developed a stochastic simulation model for Green-backed Tit population dynamics based on empirical data. We compared the simulated time-series and observed population growth rates (λ) and found that 80% (8/10 yr) of the observed λ fell within the 5th and 95th percentiles of the simulated data over the 10-yr period. Moreover, the simulated average (± standard deviation) of the geometric mean of λ over 10 yr (1.05 ± 0.07) was close to that observed from 2009 to 2019 (0.99), which provided confidence that the model effectively simulated the population growth rate of the Green-backed Tit. We conducted a sensitivity analysis for λ and found that juvenile and adult survival influenced by typhoon-induced rainfall were the greatest contributors to the variance in the growth rate of the Green-backed Tit population. With the onset of intensified seasonal precipitation associated with global warming, the population growth and density of Green-backed Tits will decline substantially. Our results suggest that under scenarios of high emissions of greenhouse gas, this local population of Green-backed Tits will not persist in the near future.

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.

scholarly journals Density Dependence and Adult Survival Drive Dynamics in Two High Elevation Amphibian Populations

Diversity ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 478
Author(s):  
Amanda M. Kissel ◽  
Simone Tenan ◽  
Erin Muths
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Density Dependence ◽  
Population Growth Rate ◽  
Geometric Mean ◽  
High Elevation ◽  
Amphibian Conservation ◽  
Adult Survival ◽  
Extrinsic Factors ◽  
Open Population

Amphibian conservation has progressed from the identification of declines to mitigation, but efforts are hampered by the lack of nuanced information about the effects of environmental characteristics and stressors on mechanistic processes of population regulation. Challenges include a paucity of long-term data and scant information about the relative roles of extrinsic (e.g., weather) and intrinsic (e.g., density dependence) factors. We used a Bayesian formulation of an open population capture-recapture model and >30 years of data to examine intrinsic and extrinsic factors regulating two adult boreal chorus frogs (Pseudacris maculata) populations. We modelled population growth rate and apparent survival directly, assessed their temporal variability, and derived estimates of recruitment. Populations were relatively stable (geometric mean population growth rate >1) and regulated by negative density dependence (i.e., higher population sizes reduced population growth rate). In the smaller population, density dependence also acted on adult survival. In the larger population, higher population growth was associated with warmer autumns. Survival estimates ranged from 0.30–0.87, per-capita recruitment was <1 in most years, and mean seniority probability was >0.50, suggesting adult survival is more important to population growth than recruitment. Our analysis indicates density dependence is a primary driver of population dynamics for P. maculata adults.

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.

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.

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 Rural–Urban Gradients and Human Population Dynamics

2019 ◽  
Vol 11 (11) ◽  
pp. 3107 ◽  
Author(s):  
Javier Montalvo ◽  
Enrique Ruiz-Labrador ◽  
Pablo Montoya-Bernabéu ◽  
Belén Acosta-Gallo
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Human Population ◽  
Population Growth Rate ◽  
Cultural Landscapes ◽  
Social Issues ◽  
Local Population ◽  
Population Mean ◽  
Management Interventions ◽  
Demographic Challenge

Rural–urban gradients offer an appropriate ecological framework for understanding relevant social issues to sustainability and policy planning. We tested the hypothesis that human population growth rate at a local scale is indirectly driven by spatial and rurality gradients, which can be applied to cultural landscapes in Mediterranean Europe. The whole of local administrative/spatial units of Spain—8125 municipalities—, previously classified into five categories along a rural–urban gradient, was used as a case study. Several geospatial patterns and associations among local average per capita population growth rate, population mean age, road accessibility, and other environmental and landscape variables linked to rurality gradients were identified by means of geographic information system (GIS) and multivariate statistics. Regression analysis was used to assess the relationship between population size changes through time and other demographic and territorial variables. Population growth rate was associated with road accessibility and rurality gradient, supporting the established hypothesis. Short-term population growth or decline was directly driven by population mean age. A visual hypothesized model of local population growth rate based on empirical evidence is presented. The results are useful for decision-makers, from local land management interventions to developing strategies and policies to address the demographic challenge.

Sensitivity and elasticity analysis of Tetranychus urticae Koch population parameters: Consequences for pest management 

2020 ◽  
Vol 25 (2) ◽  
pp. 268-284
Author(s):  
Alireza Nemati ◽  
Elham Riahi ◽  
Saadollah Houshmand
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Matrix Models ◽  
Survival Rates ◽  
Demographic Variables ◽  
Adult Survival ◽  
Egg Survival ◽  
Horticultural Crops ◽  
Structured Matrix ◽  
Different Temperatures

Sensitivity and elasticity analyses quantify the effect of an absolute and proportional change in demographic variables on population growth rate (λ), respectively. The methods are used to identify the variable(s) that have the largest influence on λ. Tetranychus urticae Koch is one of the most polyphagous tetranychid mites which has been collected from plenty plant species including agricultural and horticultural crops. In this study, sensitivity and elasticity analyses were used to investigate the effects of various demographic variables on λ at five different temperatures (15, 20, 25, 30 and 35 °C), using both age- and stage-structured matrix models. Considering the sensitivity of λ to age-dependent fecundity rates (fx), it was found that starting oviposition one day earlier was associated with the highest sensitivity compared to the other age classes, irrespective of temperature. Besides, results from both age- and stage-structured matrix models indicated that λ is more sensitive to changes in survival rates than in fecundity rates at all temperatures. Furthermore, female individuals at the ages of 46, 23, 14, 11 and 7 days had the highest contribution to population growth in comparison with other ages, when reared at the above-mentioned temperatures, respectively. Also, the sensitivity of λ to the changes in survival of adults was higher than in other stages. Besides, the elasticity to fecundity rate at the age of first reproduction was considerably higher than those associated with the age of last reproduction. The survival rates (si) generally exhibited a higher elasticity than the transition rates (gi). Overall, adult survival had the highest influence on λ followed by immature survival, egg survival, and female fecundity. Consequently, management efforts that aim at decreasing adult survival are likely to yield the best results with regard to reducing the growth rate of T. urticae.

scholarly journals Effects of liberalizing harvest regulations on Canada goose (Branta canadensis) demography in Nebraska.

2020 ◽  
Author(s):  
Timothy P Lyons ◽  
Larkin A Powell ◽  
Mark Vrtiska
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Regional Growth ◽  
Branta Canadensis ◽  
Adult Survival ◽  
Canada Goose ◽  
Canada Geese ◽  
Data Set ◽  
Early Season ◽  
Capture Recapture

Harvest regulations are used to manage populations of game species. Across their range, Canada goose Branta canadensis populations have recovered from near extirpation and are now perceived as overabundant and even a nuisance or a threat to human safety in many regions. Like many states, Nebraska has liberalized harvest regulations to increase recreation opportunities for consumptive users and to control increasing numbers of Canada geese. However, the efficacy of harvest regulations to control populations of geese is unclear. We used a live capture-recapture and dead recovery data set of more than 19,000 Canada geese banded in Nebraska 2006-2017 to determine the effect of liberalized harvest regulations on goose survival and overall growth rate. Our goals were to 1) estimate demographic parameters for Canada geese in five different regions in Nebraska 2) estimate the effect of increasing daily bag limits during the early September season and regular season on survival of hatch-year, juvenile, and adult Canada geese and 3) relate the effect of estimated changes in survival to population growth rate. We found survival (0.54-0.87), fidelity (0.14-0.99), and productivity (number of young per adult, 0.17-2.08) varied substantially among regions within Nebraska. We found increasing early season bag limits, but not regular season bag limits, reduced survival in Canada geese. However, this effect was most pronounced when comparing years without an early season to years with the highest daily bag limits used in Nebraska (eight). Survival of juvenile geese (2-3 years post-hatch) were unaffected by changes in daily bag limits during any season, though the probability of reporting was greatest for this age-class. The observed reductions in survival probability of hatch-year and adult geese due to increased daily bag limits during the early season (&lt;10%) had only weak effects on regional growth rates. Regional growth rate estimates appeared more responsive to changes in adult survival, but only decreased ~5% between years with the most liberal early-season daily bag limits to years without an early season. Our results suggest increased bag limits during the early season may reduce Canada goose survival, but has a weak impact on population growth in Nebraska.

Sign in / Sign up

Export Citation Format

Share Document