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Movement of leopard tortoises in response to environmental and climatic variables in a semi-arid environment
BACKGROUND: Tortoises (Testudinidae) occur in a wide range of environments, providing important ecosystem functions, such as seed dispersal and refuge in the form of burrows. Tortoise movement has previously been shown to be related to resource availability, reproductive status and local environment...
Autores principales: | , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5357812/ https://www.ncbi.nlm.nih.gov/pubmed/28331618 http://dx.doi.org/10.1186/s40462-017-0096-y |
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author | Drabik-Hamshare, Martyn Downs, Colleen T. |
author_facet | Drabik-Hamshare, Martyn Downs, Colleen T. |
author_sort | Drabik-Hamshare, Martyn |
collection | PubMed |
description | BACKGROUND: Tortoises (Testudinidae) occur in a wide range of environments, providing important ecosystem functions, such as seed dispersal and refuge in the form of burrows. Tortoise movement has previously been shown to be related to resource availability, reproductive status and local environmental conditions. However, understanding of the variables that drive their movement remains comparatively low. We investigated aspects of movement in leopard tortoises Stigmochelys pardalis—the largest and most abundant tortoise species in sub-Saharan Africa—in response to environmental, climatic and individual variables in the semi-arid Karoo, South Africa. We used GPS telemetry to calculate bihourly and daily movement and used generalized linear mixed models (GLMMs) to ascertain important predictor variables. RESULTS: Temperature, distance from water sources, and month were important variables for predicting both bihourly and daily movement. Our results showed that movement increased when individuals were close to known water sources, indicating that individuals close to water resources make regular long distance movements. Movement showed a positive relationship for temperature in both models, whilst rainfall was an important predictor for bihourly movement. Our results displayed aspects of seasonality, with movement highest in spring months, likely related to reproductive activities, although no sex differences were observed. CONCLUSIONS: We identified temporal and spatial conditions in which leopard tortoise movement increased. Our results further support the relationship between water as a resource and movement in leopard tortoises. Individuals used one of two basic movement behaviours in relation to water in this water scarce environment. Either an individual’s home range and movements included permanent water resources allowing internal water storage replenishment, or excluded these with reliance on food resources (such as grasses, forbs, and succulents) for water. |
format | Online Article Text |
id | pubmed-5357812 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2017 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-53578122017-03-22 Movement of leopard tortoises in response to environmental and climatic variables in a semi-arid environment Drabik-Hamshare, Martyn Downs, Colleen T. Mov Ecol Research BACKGROUND: Tortoises (Testudinidae) occur in a wide range of environments, providing important ecosystem functions, such as seed dispersal and refuge in the form of burrows. Tortoise movement has previously been shown to be related to resource availability, reproductive status and local environmental conditions. However, understanding of the variables that drive their movement remains comparatively low. We investigated aspects of movement in leopard tortoises Stigmochelys pardalis—the largest and most abundant tortoise species in sub-Saharan Africa—in response to environmental, climatic and individual variables in the semi-arid Karoo, South Africa. We used GPS telemetry to calculate bihourly and daily movement and used generalized linear mixed models (GLMMs) to ascertain important predictor variables. RESULTS: Temperature, distance from water sources, and month were important variables for predicting both bihourly and daily movement. Our results showed that movement increased when individuals were close to known water sources, indicating that individuals close to water resources make regular long distance movements. Movement showed a positive relationship for temperature in both models, whilst rainfall was an important predictor for bihourly movement. Our results displayed aspects of seasonality, with movement highest in spring months, likely related to reproductive activities, although no sex differences were observed. CONCLUSIONS: We identified temporal and spatial conditions in which leopard tortoise movement increased. Our results further support the relationship between water as a resource and movement in leopard tortoises. Individuals used one of two basic movement behaviours in relation to water in this water scarce environment. Either an individual’s home range and movements included permanent water resources allowing internal water storage replenishment, or excluded these with reliance on food resources (such as grasses, forbs, and succulents) for water. BioMed Central 2017-03-20 /pmc/articles/PMC5357812/ /pubmed/28331618 http://dx.doi.org/10.1186/s40462-017-0096-y Text en © The Author(s). 2017 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. |
spellingShingle | Research Drabik-Hamshare, Martyn Downs, Colleen T. Movement of leopard tortoises in response to environmental and climatic variables in a semi-arid environment |
title | Movement of leopard tortoises in response to environmental and climatic variables in a semi-arid environment |
title_full | Movement of leopard tortoises in response to environmental and climatic variables in a semi-arid environment |
title_fullStr | Movement of leopard tortoises in response to environmental and climatic variables in a semi-arid environment |
title_full_unstemmed | Movement of leopard tortoises in response to environmental and climatic variables in a semi-arid environment |
title_short | Movement of leopard tortoises in response to environmental and climatic variables in a semi-arid environment |
title_sort | movement of leopard tortoises in response to environmental and climatic variables in a semi-arid environment |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5357812/ https://www.ncbi.nlm.nih.gov/pubmed/28331618 http://dx.doi.org/10.1186/s40462-017-0096-y |
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