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Conquet E, Paniw M, Borrego N, Nater CR, Packer C, Ozgul A. Multifaceted density dependence: Social structure and seasonality effects on Serengeti lion demography. J Anim Ecol 2024; 93:1493-1509. [PMID: 39080877 DOI: 10.1111/1365-2656.14158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 06/27/2024] [Indexed: 10/03/2024]
Abstract
Interactions between density and environmental conditions have important effects on vital rates and consequently on population dynamics and can take complex pathways in species whose demography is strongly influenced by social context, such as the African lion, Panthera leo. In populations of such species, the response of vital rates to density can vary depending on the social structure (e.g. effects of group size or composition). However, studies assessing density dependence in populations of lions and other social species have seldom considered the effects of multiple socially explicit measures of density, and-more particularly for lions-of nomadic males. Additionally, vital-rate responses to interactions between the environment and various measures of density remain largely uninvestigated. To fill these knowledge gaps, we aimed to understand how a socially and spatially explicit consideration of density (i.e. at the local scale) and its interaction with environmental seasonality affect vital rates of lions in the Serengeti National Park, Tanzania. We used a Bayesian multistate capture-recapture model and Bayesian generalized linear mixed models to estimate lion stage-specific survival and between-stage transition rates, as well as reproduction probability and recruitment, while testing for season-specific effects of density measures at the group and home-range levels. We found evidence for several such effects. For example, resident-male survival increased more strongly with coalition size in the dry season compared with the wet season, and adult-female abundance affected subadult survival negatively in the wet season, but positively in the dry season. Additionally, while our models showed no effect of nomadic males on adult-female survival, they revealed strong effects of nomads on key processes such as reproduction and takeover dynamics. Therefore, our results highlight the importance of accounting for seasonality and social context when assessing the effects of density on vital rates of Serengeti lions and of social species more generally.
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Affiliation(s)
- Eva Conquet
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Maria Paniw
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
- Department of Conservation and Global Change, Doñana Biological Station (EBD-CSIC), Seville, Spain
| | - Natalia Borrego
- Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, Minnesota, USA
- Department for the Ecology of Animal Societies, Max Planck Institute of Animal Behavior, Konstanz, Germany
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Chloé R Nater
- The Norwegian Institute for Nature Research (NINA), Trondheim, Norway
| | - Craig Packer
- Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, Minnesota, USA
| | - Arpat Ozgul
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
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Uzal A, Martinez-Artero J, Ordiz A, Zarzo-Arias A, Penteriani V. Habitat characteristics around dens in female brown bears with cubs are density dependent. MAMMAL RES 2022. [DOI: 10.1007/s13364-022-00640-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Abstract
The mechanisms determining habitat use in animal populations have important implications for population dynamics, conservation, and management. Here, we investigated how an increase in annual numbers of brown bear females with cubs of the year (FCOY) in a growing, yet threatened population, could explain differences in the habitat characteristics around reproductive dens. Habitat characteristics around FCOY dens were compared between a low bear density period (1995–2005) and a period when the population was increasing (2006–2016). We also compared the distance to the nearest breeding area and to all other breeding areas observed during the same year. The results suggested that during the second period, breeding areas were closer to rivers, fruit trees, and anthropogenic sources of disturbance (trails, highways) than in 1995–2005. There were also shorter distances to the closest neighboring breeding area, while the mean distance among FCOY breeding areas increased as the population grew and expanded at the landscape level. These changes may reflect that the best den locations were increasingly occupied (i.e., ideal-despotic distribution), and may be further explained by the avoidance of conspecifics by FCOY in a critical time of the year, when newborn cubs are most vulnerable. We suggest that both density-dependent factors and human-related features of the landscape are crucial to understanding long-term dynamics in the habitat use of a threatened species.
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Katzenberger J, Gottschalk E, Balkenhol N, Waltert M. Density‐dependent age of first reproduction as a key factor for population dynamics: stable breeding populations mask strong floater declines in a long‐lived raptor. Anim Conserv 2021. [DOI: 10.1111/acv.12687] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jakob Katzenberger
- Dachverband Deutscher Avifaunisten (DDA) e.V. Münster Germany
- Workgroup on Endangered Species J.F. Blumenbach Institute of Zoology and Anthropology University of Goettingen Göttingen Germany
| | - Eckhard Gottschalk
- Workgroup on Endangered Species J.F. Blumenbach Institute of Zoology and Anthropology University of Goettingen Göttingen Germany
| | - Niko Balkenhol
- Wildlife Sciences University of Goettingen Göttingen Germany
| | - Matthias Waltert
- Workgroup on Endangered Species J.F. Blumenbach Institute of Zoology and Anthropology University of Goettingen Göttingen Germany
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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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Lisboa CMCA, Bajer K, Pessoa DMA, Huber MAA, Costa GC. Female Brazilian whiptail lizards (Cnemidophorus ocellifer) prefer males with high ultraviolet ornament reflectance. Behav Processes 2017; 142:33-39. [PMID: 28528929 DOI: 10.1016/j.beproc.2017.05.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 04/28/2017] [Accepted: 05/02/2017] [Indexed: 11/25/2022]
Abstract
Conspicuous colouration is an important way of social communication in many taxa. The role of ultraviolet (UV) signals in intraspecific communication has only recently been studied in lizards, and there is not a general understanding of the adaptive role of UV colouration. Colour ornaments can signal male quality in mate choice and are therefore suitable for reliably predicting the outcome of female preference. Here, we tested the potential role of UV colouration in female spatial preference in a non-territorial teiid lizard, Cnemidophorus ocellifer. We experimentally manipulated the UV reflectance of size-matched male pairs and tested the effects of our treatment on females' spatial distribution. We found that females associated with males of higher UV reflectance, suggesting that UV colour can be an important clue during mate preference decisions. Our results provide the first empirical evidence for the importance of UV colouration in female preference in a mutually ornamented lizard species.
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Affiliation(s)
- Carolina M C A Lisboa
- Laboratory of Biogeography and Macroecology, Department of Ecology, Federal University of Rio Grande do Norte, Campus Universitário Lagoa Nova, Natal RN 59078-900, Brazil.
| | - Katalin Bajer
- Laboratory of Biogeography and Macroecology, Department of Ecology, Federal University of Rio Grande do Norte, Campus Universitário Lagoa Nova, Natal RN 59078-900, Brazil; Behavioural Ecology Group, Department of Systematic Zoology and Ecology, Eötvös Loránd University Pázmány Péter sétány 1/c, H-1117 Budapest, Hungary
| | - Daniel M A Pessoa
- Laboratory of Sensory Ecology, Department of Physiology, Federal University of Rio Grande do Norte, Campus Universitário Lagoa Nova, Natal, RN 59078-900, Brazil
| | - Marc A A Huber
- Laboratory of Biogeography and Macroecology, Department of Ecology, Federal University of Rio Grande do Norte, Campus Universitário Lagoa Nova, Natal RN 59078-900, Brazil
| | - Gabriel C Costa
- Department of Biology, Auburn University at Montgomery, Montgomery, AL 36124, USA
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Urios V, Donat-Torres MP, Bechard M, Ferrer M. Movements of a juvenile Crowned Eagle (Harpyhaliaetus coronatus) tracked by satellite telemetry in central Argentina. JOURNAL OF BIOLOGICAL RESEARCH-THESSALONIKI 2015; 21:12. [PMID: 25984495 PMCID: PMC4389320 DOI: 10.1186/2241-5793-21-12] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Accepted: 03/14/2014] [Indexed: 11/10/2022]
Abstract
Background A juvenile Crowned Eagle was tagged at its nest with a satellite transmitter. The Crowned Eagle (Harpyhaliaetus coronatus) is one of the most unknown raptor species from the American continent. Their current distribution ranges from central Brazil to central Argentina, with a total population of 350–1500 individuals across this large area, being thus largely fragmented. Results During the three years of tracking the bird concentrated its movements in a range spanning for 12845 km2, but concentrating mainly in four smaller areas accounting for 3073 km2. The locations were recorded mainly over shrubland habitats (86.5%), whereas other habitats used were different types of mosaics that included cropland and natural vegetation (forest, shrubland or grassland) close to wetlands. Conclusions The home-range estimated for this individual during the whole period was 12845 km2 (according to 95% fixed kernel). However, the bird concentrated most of its movements in smaller areas (as defined above), that accounted for a total of 3073 km2 (50% fixed kernel). During these three years, most of the locations of the juvenile solitary Crowned Eagle were recorded over shrubland habitats (86.5% of the locations). Understanding in a more detailed way the juvenile ranging behaviour and habitat preferences would be of great importance for the conservation of the Crowned Eagle.
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Affiliation(s)
- Vicente Urios
- Estación Biológica Terra Natura, Universidad de Alicante, Alicante, E-03080 Spain
| | - Maria Pilar Donat-Torres
- Instituto de Investigación para la Gestión Integrada de Zonas Costeras IGIC, Universidad Politecnica de Valencia, Gandia, E-46730 Spain
| | - Mark Bechard
- Department of Biology, Boise State University, Boise, ID 83725-1515 USA
| | - Miguel Ferrer
- Departamento de Etología y Conservación de la Biodiversidad, Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas CSIC, Sevilla, E-41092 Spain
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Penteriani V, Delgado MDM, Lokki H. Global Warming May Depress Avian Population Fecundity by Selecting Against Early-Breeding, High-Quality Individuals in Northern Populations of Single-Brooded, Long-Lived Species. ANN ZOOL FENN 2014. [DOI: 10.5735/086.051.0404] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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9
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Weston ED, Whitfield DP, Travis JMJ, Lambin X. When do young birds disperse? Tests from studies of golden eagles in Scotland. BMC Ecol 2013; 13:42. [PMID: 24192328 PMCID: PMC3833264 DOI: 10.1186/1472-6785-13-42] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 10/03/2013] [Indexed: 11/21/2022] Open
Abstract
Background Dispersal comprises three broad stages - departure from the natal or breeding locations, subsequent travel, and settlement. These stages are difficult to measure, and vary considerably between sexes, age classes, individuals and geographically. We used tracking data from 24 golden eagles, fitted with long-lived GPS satellite transmitters as nestlings, which we followed during their first year. We estimated the timing of emigration from natal sites using ten previously published methods. We propose and evaluate two new methods. The first of these uses published ranging distances of parents as a measure of the natal home range, with the requirement that juveniles must exceed it for a minimum of 10 days (a literature-based measure of the maximum time that a juvenile can survive without food from its parents). The second method uses the biggest difference in the proportion of locations inside and outside of the natal home range smoothed over a 30 day period to assign the point of emigration. We used the latter as the standard against which we compared the ten published methods. Results The start of golden eagle dispersal occurred from 39 until 250 days after fledging (based on method 12). Previously published methods provided very different estimates of the point of emigration with a general tendency for most to apparently assign it prematurely. By contrast the two methods we proposed provided very similar estimates for the point of emigration that under visual examination appeared to fit the definition of emigration much better. Conclusions We have used simple methods to decide when an individual has dispersed - they are rigorous and repeatable. Despite one method requiring much more information, both methods provided robust estimates for when individuals emigrated at the start of natal dispersal. Considerable individual variation in recorded behaviour appears to account for the difficulty capturing the point of emigration and these results demonstrate the potential pitfalls associated with species exhibiting complex dispersal behaviour. We anticipate that coupled with the rapidly increasing availability of tracking data, our new methods will, for at least some species, provide a far simpler and more biologically representative approach to determine the timing of emigration.
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Affiliation(s)
- Ewan D Weston
- Institute of Biological and Environmental Sciences, Zoology Building, University of Aberdeen, Aberdeen AB24 2TZ, UK.
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10
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Soutullo A, López-López P, Cortés G, Urios V, Ferrer M. Exploring juvenile golden eagles' dispersal movements at two different temporal scales. ETHOL ECOL EVOL 2013. [DOI: 10.1080/03949370.2012.742463] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Ferrer M, Bildstein K, Penteriani V, Casado E, de Lucas M. Why birds with deferred sexual maturity are sedentary on islands: a systematic review. PLoS One 2011; 6:e22056. [PMID: 21811559 PMCID: PMC3139619 DOI: 10.1371/journal.pone.0022056] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 06/14/2011] [Indexed: 11/19/2022] Open
Abstract
Background Island faunas have played central roles in the development of evolutionary biology and ecology. Birds are among the most studied organisms on islands, in part because of their dispersal powers linked to migration. Even so, we lack of information about differences in the movement ecology of island versus mainland populations of birds. Methodology/Principal Findings Here we present a new general pattern indicating that large birds with deferred sexual maturity are sedentary on islands, and that they become so even when they are migratory on the mainland. Density-dependent variation in the age at first breeding affects the survivorship of insular populations and this, in turn, affects the movement ecology of large birds. Because density-dependent variation in the age of first breeding is critical to the long-term survival of small isolated populations of long-lived species, migratory forms can successfully colonize islands only if they become sedentary once there. Analyses of the movement ecology of continental and insular populations of 314 species of raptors, 113 species of Ciconiiformes and 136 species of passerines, along with individual-based population simulations confirm this prediction. Conclusions This finding has several consequences for speciation, colonization and survival of small isolated population of species with deferred sexual maturity.
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Affiliation(s)
- Miguel Ferrer
- Department of Ethology and Biodiversity Conservation, Estación Biológica de Doñana, Consejo Superior de Investigaciones Cientificas (CSIC), Seville, Spain.
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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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del Mar Delgado M, Ratikainen II, Kokko H. Inertia: the discrepancy between individual and common good in dispersal and prospecting behaviour. Biol Rev Camb Philos Soc 2010; 86:717-32. [DOI: 10.1111/j.1469-185x.2010.00167.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Carrascal LM, Seoane J. Linking density, productivity and trends of an endangered species: The Bonelli's eagle in Spain. ACTA OECOLOGICA 2009. [DOI: 10.1016/j.actao.2009.03.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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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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del Mar Delgado M, Penteriani V. Behavioral States Help Translate Dispersal Movements into Spatial Distribution Patterns of Floaters. Am Nat 2008; 172:475-85. [PMID: 18729727 DOI: 10.1086/590964] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- María del Mar Delgado
- Department of Conservation Biology, Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas, Avenida de María Luisa s/n, Pabellón del Perú, Apartado 1056, 41013 Seville, Spain.
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Ferrer M, Penteriani V. Non-independence of demographic parameters: positive density-dependent fecundity in eagles. J Appl Ecol 2008. [DOI: 10.1111/j.1365-2664.2008.01497.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Pontier D, Fouchet D, Bried J, Bahi-Jaber N. Limited nest site availability helps seabirds to survive cat predation on islands. Ecol Modell 2008. [DOI: 10.1016/j.ecolmodel.2008.02.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Penteriani V, Otalora F, Ferrer M. Floater mortality within settlement areas can explain the Allee effect in breeding populations. Ecol Modell 2008. [DOI: 10.1016/j.ecolmodel.2007.11.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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When similar ecological patterns in time emerge from different initial conditions: equifinality in the breeding performance of animal populations. ECOLOGICAL COMPLEXITY 2008. [DOI: 10.1016/j.ecocom.2007.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Schmidt BR, Schaub M, Steinfartz S. Apparent survival of the salamander Salamandra salamandra is low because of high migratory activity. Front Zool 2007; 4:19. [PMID: 17803829 PMCID: PMC2020470 DOI: 10.1186/1742-9994-4-19] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Accepted: 09/06/2007] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Understanding the demographic processes underlying population dynamics is a central theme in ecology. Populations decline if losses from the population (i.e., mortality and emigration) exceed gains (i.e., recruitment and immigration). Amphibians are thought to exhibit little movement even though local populations often fluctuate dramatically and are likely to go exinct if there is no rescue effect through immigration from nearby populations. Terrestrial salamanders are generally portrayed as amphibians with low migratory activity. Our study uses demographic analysis as a key to unravel whether emigration or mortality is the main cause of "losses" from the population. In particular, we use the analysis to challenge the common belief that terrestrial salamanders show low migratory activity. RESULTS The mark-recapture analysis of adult salamanders showed that monthly survival was high (> 90%) without a seasonal pattern. These estimates, however, translate into rather low rates of local annual survival of only ~40% and suggest that emigration was important. The estimated probability of emigration was 49%. CONCLUSION Our analysis shows that terrestrial salamanders exhibit more migratory activity than commonly thought. This may be due either because the spatial extent of salamander populations is underestimated or because there is a substantial exchange of individuals between populations. Our current results are in line with several other studies that suggest high migratory activity in amphibians. In particular, many amphibian populations may be characterized by high proportions of transients and/or floaters.
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Affiliation(s)
- Benedikt R Schmidt
- Zoologisches Institut, Universität Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
- KARCH, Passage Maximilien-de-Meuron 6, 2000 Neuchâtel, Switzerland
| | - Michael Schaub
- Conservation Biology, Zoologisches Institut, Universität Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
- Schweizerische Vogelwarte, 6204 Sempach, Switzerland
| | - Sebastian Steinfartz
- University of Bielefeld, Department of Animal Behavior, Morgenbreede 45, 33615 Bielefeld, Germany
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