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Can individual and social patterns of resource use buffer animal populations against resource decline?

Banks SC, Lindenmayer DB, Wood JT, McBurney L, Blair D, Blyton MD - PLoS ONE (2013)

Bottom Line: Analyses of data from 160 sites surveyed from 1997 to 2007 showed that hollow tree availability was positively associated with abundance of the mountain brushtail possum, the agile antechinus and the greater glider.Notably, the relationship between abundance and hollow tree availability was significantly less than 1:1 for all species.Our results show that individual and social aspects of resource use are not always static in response to resource availability and support the need to account for dynamic resource use patterns in predictive models of animal distribution and abundance.

View Article: PubMed Central - PubMed

Affiliation: The Fenner School of Environment and Society, The Australian National University, Canberra, Australian Capital Territory, Australia. Sam.Banks@anu.edu.au

ABSTRACT
Species in many ecosystems are facing declines of key resources. If we are to understand and predict the effects of resource loss on natural populations, we need to understand whether and how the way animals use resources changes under resource decline. We investigated how the abundance of arboreal marsupials varies in response to a critical resource, hollow-bearing trees. Principally, we asked what mechanisms mediate the relationship between resources and abundance? Do animals use a greater or smaller proportion of the remaining resource, and is there a change in cooperative resource use (den sharing), as the availability of hollow trees declines? Analyses of data from 160 sites surveyed from 1997 to 2007 showed that hollow tree availability was positively associated with abundance of the mountain brushtail possum, the agile antechinus and the greater glider. The abundance of Leadbeater's possum was primarily influenced by forest age. Notably, the relationship between abundance and hollow tree availability was significantly less than 1:1 for all species. This was due primarily to a significant increase by all species in the proportional use of hollow-bearing trees where the abundance of this resource was low. The resource-sharing response was weaker and inconsistent among species. Two species, the mountain brushtail possum and the agile antechinus, showed significant but contrasting relationships between the number of animals per occupied tree and hollow tree abundance. The discrepancies between the species can be explained partly by differences in several aspects of the species' biology, including body size, types of hollows used and social behaviour as it relates to hollow use. Our results show that individual and social aspects of resource use are not always static in response to resource availability and support the need to account for dynamic resource use patterns in predictive models of animal distribution and abundance.

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Model predictions for the greater glider of the number of animals per site (grey), the probability of occupancy per tree (red) and the number of animals per occupied tree (black) in relation to the number of hollow trees per 1 ha site.Dotted lines show 95% confidence intervals. Predictions were averaged over the non-represented variables (e.g. tree form). The number of animals per occupied tree (black lines) had a non-significant relationship with hollow tree abundance.
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pone-0053672-g004: Model predictions for the greater glider of the number of animals per site (grey), the probability of occupancy per tree (red) and the number of animals per occupied tree (black) in relation to the number of hollow trees per 1 ha site.Dotted lines show 95% confidence intervals. Predictions were averaged over the non-represented variables (e.g. tree form). The number of animals per occupied tree (black lines) had a non-significant relationship with hollow tree abundance.

Mentions: We observed a mean of 2.26 (range 0–21) animals per site (over all species). The most commonly recorded species were the mountain brushtail possum (329 individual records) and the greater glider (328), followed by Leadbeater’s possum (175) and the agile antechinus (160) from 440 site surveys from 1997 to 2007. For three species, the number of individuals recorded per site showed a significant positive relationship with the number of hollow trees (Table 1, Figures 3, 4, and 5). For Leadbeater’s possum, but no other species, we found a significant effect of forest age on site level abundance (this species was most abundant in young regrowth forest that germinated after a 1983 wildfire), but no effect of hollow tree availability (P = 0.082; Table 1, Figure 6).


Can individual and social patterns of resource use buffer animal populations against resource decline?

Banks SC, Lindenmayer DB, Wood JT, McBurney L, Blair D, Blyton MD - PLoS ONE (2013)

Model predictions for the greater glider of the number of animals per site (grey), the probability of occupancy per tree (red) and the number of animals per occupied tree (black) in relation to the number of hollow trees per 1 ha site.Dotted lines show 95% confidence intervals. Predictions were averaged over the non-represented variables (e.g. tree form). The number of animals per occupied tree (black lines) had a non-significant relationship with hollow tree abundance.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3539978&req=5

pone-0053672-g004: Model predictions for the greater glider of the number of animals per site (grey), the probability of occupancy per tree (red) and the number of animals per occupied tree (black) in relation to the number of hollow trees per 1 ha site.Dotted lines show 95% confidence intervals. Predictions were averaged over the non-represented variables (e.g. tree form). The number of animals per occupied tree (black lines) had a non-significant relationship with hollow tree abundance.
Mentions: We observed a mean of 2.26 (range 0–21) animals per site (over all species). The most commonly recorded species were the mountain brushtail possum (329 individual records) and the greater glider (328), followed by Leadbeater’s possum (175) and the agile antechinus (160) from 440 site surveys from 1997 to 2007. For three species, the number of individuals recorded per site showed a significant positive relationship with the number of hollow trees (Table 1, Figures 3, 4, and 5). For Leadbeater’s possum, but no other species, we found a significant effect of forest age on site level abundance (this species was most abundant in young regrowth forest that germinated after a 1983 wildfire), but no effect of hollow tree availability (P = 0.082; Table 1, Figure 6).

Bottom Line: Analyses of data from 160 sites surveyed from 1997 to 2007 showed that hollow tree availability was positively associated with abundance of the mountain brushtail possum, the agile antechinus and the greater glider.Notably, the relationship between abundance and hollow tree availability was significantly less than 1:1 for all species.Our results show that individual and social aspects of resource use are not always static in response to resource availability and support the need to account for dynamic resource use patterns in predictive models of animal distribution and abundance.

View Article: PubMed Central - PubMed

Affiliation: The Fenner School of Environment and Society, The Australian National University, Canberra, Australian Capital Territory, Australia. Sam.Banks@anu.edu.au

ABSTRACT
Species in many ecosystems are facing declines of key resources. If we are to understand and predict the effects of resource loss on natural populations, we need to understand whether and how the way animals use resources changes under resource decline. We investigated how the abundance of arboreal marsupials varies in response to a critical resource, hollow-bearing trees. Principally, we asked what mechanisms mediate the relationship between resources and abundance? Do animals use a greater or smaller proportion of the remaining resource, and is there a change in cooperative resource use (den sharing), as the availability of hollow trees declines? Analyses of data from 160 sites surveyed from 1997 to 2007 showed that hollow tree availability was positively associated with abundance of the mountain brushtail possum, the agile antechinus and the greater glider. The abundance of Leadbeater's possum was primarily influenced by forest age. Notably, the relationship between abundance and hollow tree availability was significantly less than 1:1 for all species. This was due primarily to a significant increase by all species in the proportional use of hollow-bearing trees where the abundance of this resource was low. The resource-sharing response was weaker and inconsistent among species. Two species, the mountain brushtail possum and the agile antechinus, showed significant but contrasting relationships between the number of animals per occupied tree and hollow tree abundance. The discrepancies between the species can be explained partly by differences in several aspects of the species' biology, including body size, types of hollows used and social behaviour as it relates to hollow use. Our results show that individual and social aspects of resource use are not always static in response to resource availability and support the need to account for dynamic resource use patterns in predictive models of animal distribution and abundance.

Show MeSH