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 (<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.

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.

A study of Canada geese, Branta canadensis, nesting on islands in southeastern Alberta

1970 ◽  
Vol 48 (2) ◽  
pp. 235-240 ◽  
Author(s):  
Kees Vermeer
Keyword(s):  
Egg Laying ◽  
Water Levels ◽  
Branta Canadensis ◽  
Canada Goose ◽  
Canada Geese ◽  
Uniform Spacing ◽  
Incubation Periods

Canada goose clutches situated on islands in Dowling Lake and Lake Newell, Alberta, were checked from laying to hatching. Egg-laying intervals averaged 1.87 days and incubation periods 26.8 days. The distribution of nests showed a significant deviation from randomness in the direction of uniform spacing. Causes of extensive hatching failure at Dowling Lake were predation and desertion. Predation by coyotes was facilitated by low water levels. A preference for nesting on islands appears to be a mechanism to counteract mammalian predation.

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 A white feathered area on the forehead is more common in hybrids of Greylag Goose Anser anser and Greater Canada Goose Branta canadensis than in the parent species

Ornis Svecica ◽  
2011 ◽  
Vol 21 (1) ◽  
pp. 37-44
Author(s):  
C G Gustavsson
Keyword(s):  
Quantitative Comparison ◽  
Branta Canadensis ◽  
Canada Goose ◽  
Canada Geese ◽  
Parent Species ◽  
Anser Anser ◽  
White Area ◽  
Greylag Goose ◽  
Greylag Geese

This study evaluated prevalence and extent of white areas on heads of Greylag Goose × Greater Canada Goose hybrids. A white area which bordered the bill and then to various degrees extended over the forehead was found in 17 out of 20 hybrids. This was significantly more common in the hybrids than in the parent species. The white areas in the hybrids were also significantly larger than in those 82 out of 191 adult Greylag Geese which had some amount of white area. There were too few Greater Canada Geese with a white area outside the normal pale cheek patch to make a meaningful similar quantitative comparison also with them. No white area was seen in the three presumed 1st Calendar Year (CY) hybrids but when two of them were seen again in September of the 2nd CY there were some pale feathers that were interpreted as the beginning of white areas. The white areas in hybrids are therefore regarded to be adult features which like in several pure Anser species begin to develop during the 2nd CY.

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.

scholarly journals A Test for the Underlying State-Structure of Hidden Markov Models: Partially Observed Capture-Recapture Data

2021 ◽  
Vol 9 ◽  
Author(s):  
Anita Jeyam ◽  
Rachel S. McCrea ◽  
Roger Pradel
Keyword(s):  
Hidden Markov Models ◽  
Markov Models ◽  
Hidden Markov ◽  
Canada Geese ◽  
State Structure ◽  
Data Set ◽  
Partial Observations ◽  
Partially Observed ◽  
Capture Recapture ◽  
Special Case

Hidden Markov models (HMMs) are being widely used in the field of ecological modeling, however determining the number of underlying states in an HMM remains a challenge. Here we examine a special case of capture-recapture models for open populations, where some animals are observed but it is not possible to ascertain their state (partial observations), whilst the other animals' states are assigned without error (complete observations). We propose a mixture test of the underlying state structure generating the partial observations, which assesses whether they are compatible with the set of states observed in the complete observations. We demonstrate the good performance of the test using simulation and through application to a data set of Canada Geese.

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.

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.

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