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Whitfield DP, Fielding AH, Anderson D, Benn S, Dennis R, Grant J, Weston ED. Age of First Territory Settlement of Golden Eagles Aquila chrysaetos in a Variable Competitive Landscape. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.743598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
With life-history traits involving high survival, low reproductive output, years of natal dispersal and deferred maturity, the population ecology and behaviour of large raptors which occur at low densities can be difficult to study. The age at which large raptors first settle on a prospective breeding territory receives relatively little attention, but is a key metric in population modelling including, for example, projections of reintroduction projects. It can also be a barometer of the “health” of populations and the availability of breeding opportunities. The advancement of GPS-telemetry has proved invaluable in gaining insights into several aspects of large raptor ecology and behaviour. Age of first territory settlement (AFTS) is one such aspect. AFTS is important in modelling population trajectories and considering individuals’ lifetime reproductive success. We used an algorithm based on GPS-records from dispersing Golden Eagles tagged as nestlings in Scotland to estimate AFTS. While the lifespan of GPS-tags can bias against settlement dates of older birds, they can also potentially reveal settlement ages difficult or impossible to discern from other methods. We found a range of ages for AFTS, including those in their second calendar year; much younger than previously documented by other methods. Ground-truthing – when possible and if inevitably slightly delayed – confirmed territory occupation on field-based survey criteria. We found that eagles settled younger in vacant territories and when older in occupied existing territories. Birds’ sex had no effect on AFTS. Birds which dispersed earlier from their natal territory (indicative of “quality” from some previous research) had no association with AFTS. Our results indicate that within technological temporal limits GPS-data can provide for accurate and precise estimations of AFTS including early settlement not consistently or precisely recorded by other methods. Within our study’s variable competitive landscape we found that AFTS was associated with the availability of territorial opportunities but not with the timing of dispersal. These findings have consequences for studying and understanding large raptor population dynamics.
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Margalida A, Jiménez J, Martínez JM, Sesé JA, García‐Ferré D, Llamas A, Razin M, Colomer M, Arroyo B. An assessment of population size and demographic drivers of the Bearded Vulture using integrated population models. ECOL MONOGR 2020. [DOI: 10.1002/ecm.1414] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Antoni Margalida
- Instituto de Investigación en Recursos Cinegéticos (IREC, CSIC‐UCLM‐JCCM) E‐13005 Ciudad Real Spain
- Division of Conservation Biology Institute of Ecology and Evolution University of Bern Baltzerstrasse 6 CH‐3012 Bern Switzerland
| | - José Jiménez
- Instituto de Investigación en Recursos Cinegéticos (IREC, CSIC‐UCLM‐JCCM) E‐13005 Ciudad Real Spain
| | - José M. Martínez
- Gobierno de Aragón Subdirección General de Desarrollo Rural y Sostenibilidad Departamento Medio Ambiente C/ General Lasheras 8 E‐22003 Huesca Spain
| | - José A. Sesé
- Gobierno de Aragón Subdirección General de Desarrollo Rural y Sostenibilidad Departamento Medio Ambiente C/ General Lasheras 8 E‐22003 Huesca Spain
| | - Diego García‐Ferré
- Generalitat de Catalunya Departament de Territori i Sostenibilitat Servei de Fauna i Flora. C/Provença 204 08036 Barcelona Spain
| | - Alfonso Llamas
- Gestión Ambiental de Navarra C/ Padre Adoain 219 E‐31015 Pamplona Spain
| | - Martine Razin
- Ligue pour la Protection des Oiseaux (LPO/BirdLife) Fonderies Royales 8/10 rue du Dr Pujos F‐17305 Rochefort Cedex France
| | - MªÀngels Colomer
- Department of Mathematics Faculty of Life Sciences and Engineering University of Lleida E‐25198 Lleida Spain
| | - Beatriz Arroyo
- Instituto de Investigación en Recursos Cinegéticos (IREC, CSIC‐UCLM‐JCCM) E‐13005 Ciudad Real Spain
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Can landscape characteristics help explain the different trends of Cantabrian brown bear subpopulations? MAMMAL RES 2019. [DOI: 10.1007/s13364-019-00440-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Robles H, Ciudad C. Floaters may buffer the extinction risk of small populations: an empirical assessment. Proc Biol Sci 2017; 284:rspb.2017.0074. [PMID: 28424345 DOI: 10.1098/rspb.2017.0074] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 03/17/2017] [Indexed: 11/12/2022] Open
Abstract
The high extinction risk of small populations is commonly explained by reductions in fecundity and breeder survival associated with demographic and environmental stochasticity. However, ecological theory suggests that population extinctions may also arise from reductions in the number of floaters able to replace the lost breeders. This can be particularly plausible under harsh fragmentation scenarios, where species must survive as small populations subjected to severe effects of stochasticity. Using a woodpecker study in fragmented habitats (2004-2016), we provide here empirical support for the largely neglected hypothesis that floaters buffer population extirpation risks. After controlling for population size, patch size and the intrinsic quality of habitat, populations in patches with floaters had a lower extinction probability than populations in patches without floaters (0.013 versus 0.131). Floaters, which often replace the lost breeders, were less likely to occur in small and low-quality patches, showing that population extirpations may arise from unnoticed reductions in floater numbers in poor-quality habitats. We argue that adequate pools of the typically overlooked floaters may buffer extirpation risks by reducing the detrimental impacts of demographic and environmental stochasticity. However, unravelling the influence of floaters in buffering stochastic effects and promoting population stability require additional studies in an ample array of species and stochastic scenarios.
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Affiliation(s)
- Hugo Robles
- EVECO, Department of Biology, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1, 2610 Wilrijk, Belgium .,GIBE, University of A Coruña, Campus Zapateira, 15008 A Coruña, Spain
| | - Carlos Ciudad
- Department of Biodiversity and Environmental Management, University of León, Campus de Vegazana s/n, 24071 León, Spain.,ECOGESFOR, Technical University of Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
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McClure CJW, Pauli BP, Heath JA. Simulations reveal the power and peril of artificial breeding sites for monitoring and managing animals. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2017; 27:1155-1166. [PMID: 28117915 DOI: 10.1002/eap.1509] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 01/10/2017] [Accepted: 01/11/2017] [Indexed: 06/06/2023]
Abstract
Despite common use, the efficacy of artificial breeding sites (e.g., nest boxes, bat houses, artificial burrows) as tools for monitoring and managing animals depends on the demography of target populations and availability of natural sites. Yet, the conditions enabling artificial breeding sites to be useful or informative have yet to be articulated. We use a stochastic simulation model to determine situations where artificial breeding sites are either useful or disadvantageous for monitoring and managing animals. Artificial breeding sites are a convenient tool for monitoring animals and therefore occupancy of artificial breeding sites is often used as an index of population levels. However, systematic changes in availability of sites that are not monitored might induce trends in occupancy of monitored sites, a situation rarely considered by monitoring programs. We therefore examine how systematic changes in unmonitored sites could bias inference from trends in the occupancy of monitored sites. Our model also allows us to examine effects on population levels if artificial breeding sites either increase or decrease population vital rates (survival and fecundity). We demonstrate that trends in occupancy of monitored sites are misleading if the number of unmonitored sites changes over time. Further, breeding site fidelity can cause an initial lag in occupancy of newly installed sites that could be misinterpreted as an increasing population, even when the population has been continuously declining. Importantly, provisioning of artificial breeding sites only benefits populations if breeding sites are limiting or if artificial sites increase vital rates. There are many situations where installation of artificial breeding sites, and their use in monitoring, can have unintended consequences. Managers should therefore not assume that provision of artificial breeding sites will necessarily benefit populations. Further, trends in occupancy of artificial breeding sites should be interpreted in light of potential changes in the availability of unmonitored sites and the potential of lags in occupancy owing to site fidelity.
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Affiliation(s)
| | - Benjamin P Pauli
- Department of Biological Sciences and Raptor Research Center, Boise State University, 1910 University Drive, Boise, Idaho, 83725, USA
| | - Julie A Heath
- Department of Biological Sciences and Raptor Research Center, Boise State University, 1910 University Drive, Boise, Idaho, 83725, USA
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SASMAL SOURAVKUMAR, MANDAL DIBYENDUSEKHAR, CHATTOPADHYAY JOYDEV. A PREDATOR-PEST MODEL WITH ALLEE EFFECT AND PEST CULLING AND ADDITIONAL FOOD PROVISION TO THE PREDATOR — APPLICATION TO PEST CONTROL. J BIOL SYST 2017. [DOI: 10.1142/s0218339017500152] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The harmful effects of insect pests on human health and agricultural output are a major global concern. Frequent use of chemical pesticides as a means of pest control can have detrimental effects on the environment, resulting in water and soil pollution, food toxicity, resistance to pesticides, etc. As a result, there is an urgent need to develop a biological pest-control approach that would mitigate these harmful effects. The main purpose of the present study is to explore the interaction between strong Allee effects in the pest with other biological control mechanisms, such as providing additional food to the predator and pest culling as a means of proposing an efficient pest-control policy. To achieve this goal, local stability analysis around the equilibria, possible bifurcation and some basic dynamical features of the system was performed. Our work focuses on the basin of stability in multiple stable regions of the model, which yields the probability of convergence of each equilibrium for a given set of different initial conditions. The system exhibits bi-stability and tri-stability of the equilibria. Our findings indicate that providing additional food to the predator can be an efficient stand-alone pest control strategy, which can, if needed, be combined with other methods.
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Affiliation(s)
- SOURAV KUMAR SASMAL
- Agricultural and Ecological Research Unit, Indian Statistical Institute, 203, B. T. Road, Kolkata 700108, India
| | - DIBYENDU SEKHAR MANDAL
- Agricultural and Ecological Research Unit, Indian Statistical Institute, 203, B. T. Road, Kolkata 700108, India
| | - JOYDEV CHATTOPADHYAY
- Agricultural and Ecological Research Unit, Indian Statistical Institute, 203, B. T. Road, Kolkata 700108, India
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Lee AM, Reid JM, Beissinger SR. Modelling effects of nonbreeders on population growth estimates. J Anim Ecol 2016; 86:75-87. [PMID: 27625075 DOI: 10.1111/1365-2656.12592] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Accepted: 09/03/2016] [Indexed: 01/29/2023]
Abstract
Adult individuals that do not breed in a given year occur in a wide range of natural populations. However, such nonbreeders are often ignored in theoretical and empirical population studies, limiting our knowledge of how nonbreeders affect realized and estimated population dynamics and potentially impeding projection of deterministic and stochastic population growth rates. We present and analyse a general modelling framework for systems where breeders and nonbreeders differ in key demographic rates, incorporating different forms of nonbreeding, different life histories and frequency-dependent effects of nonbreeders on demographic rates of breeders. Comparisons of estimates of deterministic population growth rate, λ, and demographic variance, σd2, from models with and without distinct nonbreeder classes show that models that do not explicitly incorporate nonbreeders give upwardly biased estimates of σd2, particularly when the equilibrium ratio of nonbreeders to breeders, Nnb∗/Nb∗, is high. Estimates of λ from empirical observations of breeders only are substantially inflated when individuals frequently re-enter the breeding population after periods of nonbreeding. Sensitivity analyses of diverse parameterizations of our model framework, with and without negative frequency-dependent effects of nonbreeders on breeder demographic rates, show how changes in demographic rates of breeders vs. nonbreeders differentially affect λ. In particular, λ is most sensitive to nonbreeder parameters in long-lived species, when Nnb∗/Nb∗>0, and when individuals are unlikely to breed at several consecutive time steps. Our results demonstrate that failing to account for nonbreeders in population studies can obscure low population growth rates that should cause management concern. Quantifying the size and demography of the nonbreeding section of populations and modelling appropriate demographic structuring is therefore essential to evaluate nonbreeders' influence on deterministic and stochastic population dynamics.
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Affiliation(s)
- Aline M Lee
- Department of Environmental Science, Policy & Management, University of California, Berkeley, CA, 94720-3114, USA.,Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, AB24 2TZ, UK
| | - Jane M Reid
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, AB24 2TZ, UK
| | - Steven R Beissinger
- Department of Environmental Science, Policy & Management, University of California, Berkeley, CA, 94720-3114, USA.,Museum of Vertebrate Zoology, University of California, Berkeley, CA, 94720-3160, USA
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Dettling MD, Seavy NE, Howell CA, Gardali T. Current Status of Western Yellow-Billed Cuckoo along the Sacramento and Feather Rivers, California. PLoS One 2015; 10:e0125198. [PMID: 25915801 PMCID: PMC4411113 DOI: 10.1371/journal.pone.0125198] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 03/20/2015] [Indexed: 11/29/2022] Open
Abstract
To evaluate the current status of the western population of the Yellow-billed Cuckoo (Coccyzus americanus) along the Sacramento and Feather rivers in California's Sacramento Valley, we conducted extensive call playback surveys in 2012 and 2013. We also quantified the amount and distribution of potential habitat. Our survey transects were randomly located and spatially balanced to sample representative areas of the potential habitat. We estimated that the total area of potential habitat was 8,134 ha along the Sacramento River and 2,052 ha along the Feather River, for a total of 10,186 ha. Large-scale restoration efforts have created potential habitat along both of these rivers. Despite this increase in the amount of habitat, the number of cuckoos we detected was extremely low. There were 8 detection occasions in 2012 and 10 occasions in 2013 on the Sacramento River, in both restored and remnant habitat. We had no detections on the Feather River in either year. We compared our results to 10 historic studies from as far back as 1972 and found that the Yellow-billed Cuckoo had unprecedentedly low numbers in 2010, 2012, and 2013. The current limiting factor for the Yellow-billed Cuckoo in the Sacramento Valley is likely not the amount of appropriate vegetation, as restoration has created more habitat over the last 30 years. Reasons for the cuckoo decline on the Sacramento and Feather rivers are unclear.
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Affiliation(s)
- Mark D. Dettling
- Point Blue Conservation Science, Petaluma, California, United States of America
| | - Nathaniel E. Seavy
- Point Blue Conservation Science, Petaluma, California, United States of America
| | - Christine A. Howell
- Point Blue Conservation Science, Petaluma, California, United States of America
| | - Thomas Gardali
- Point Blue Conservation Science, Petaluma, California, United States of America
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Penteriani V, Ferrer M, Delgado MM. Floater strategies and dynamics in birds, and their importance in conservation biology: towards an understanding of nonbreeders in avian populations. Anim Conserv 2011. [DOI: 10.1111/j.1469-1795.2010.00433.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Penteriani V, Ferrer M, Otalora F, del Mar Delgado M. When individuals senesce: the ‘Florida effect’ on stable populations of territorial, long-lived birds. OIKOS 2009. [DOI: 10.1111/j.1600-0706.2008.17190.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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