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11 - Direct behavioral indicators as a conservation and management tool
- from Part IV - Behavioral indicators
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- By Burt P. Kotler, Ben-Gurion University of the Negev, Israel, Douglas W. Morris, Lakehead University, Canada, Joel S. Brown, University of Illinois at Chicago, USA
- Edited by Oded Berger-Tal, Ben-Gurion University of the Negev, Israel, David Saltz, Ben-Gurion University of the Negev, Israel
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- Book:
- Conservation Behavior
- Published online:
- 05 April 2016
- Print publication:
- 03 May 2016, pp 307-351
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- Chapter
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Summary
INTRODUCTION
Here is an exercise to try with your students or colleagues regarding wildlife conservation and management. Tell them they are managing an area containing a population of an endangered, charismatic, flagship wildlife species, say mountain nyala in Bale Mountains National Park, Ethiopia. Invite them to write down the one or two things they would most want to know in order to best manage the population. The answers will vary. Some may inquire into the population size or density; others may want to know what the nyala are eating; others may want to know about the nyalas’ levels of genetic heterozygosity. But what we really want to know is “what is the state of the population in terms of growth rate and relationship to resource density?” “what are the threats to the population?” and “what are the population's prospects for the future?” Are these questions we can answer? Will knowledge of population size or genetics or diet allow us to answer these? Or can answers best be obtained from other information? If so, how can such information be acquired? What are the best indicators?
Ideally, indicators of population well-being must be reliable. Further, they should be easy to measure, respond quickly to environmental change and forecast the future. Measurements of population sizes are frequently used in management decisions and may excel in identifying when small population issues are of concern, but are woefully inadequate as indicators of population processes. Such metrics do not necessarily respond quickly to environmental change. Most populations experience time-lagged dynamics. But time lags mean that density is a trailing indicator of current conditions. We must search elsewhere for leading indicators – indicators that predict the future rather than simply recapitulating the past. Perhaps we can find our indicators in the traits of organisms that have been shaped by evolution (Grafen 1982, Lucas & Grafen 1985, Mitchell & Valone 1990). One attractive class of characteristics comes from foraging theory and measures of behavior (Stephens & Krebs 1986). These can be classified into behavioral indicators based on diet, patch use or habitat selection.
Consider indicators of population well-being further. An example involving the Baltic tellin (Macoma balthica) illustrates this well. Baltic tellins, benthic bivalves from the Dutch Wadden Sea, suffer predation from red knots (Calidris canutus) (van Gils et al. 2009).
Effects of habitat, group-size, sex-age class and seasonal variation on the behavioural responses of the mountain nyala (Tragelaphus buxtoni) in Munessa, Ethiopia
- Solomon A. Tadesse, Burt P. Kotler
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- Journal:
- Journal of Tropical Ecology / Volume 30 / Issue 1 / January 2014
- Published online by Cambridge University Press:
- 11 November 2013, pp. 33-43
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- Article
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Activity patterns of animals are generally influenced by many factors. We hypothesized that the behavioural responses (i.e. activity time-budget allocated to vigilance, feeding and moving) of mountain nyala (Tragelaphus buxtoni) should vary with habitat type, season, group-size and sex-age class. We randomly established a total of 12 permanent walking transects with the aid of a GPS device across three major habitat types used by the mountain nyala (i.e. four transects in each habitat). Following each transect, we conducted focal-animal observations to quantify the time-budget allocated to vigilance, feeding and moving. A total of 119 and 116 focal-animals were assessed in the wet and dry season respectively. Moreover, along each transect, seven habitat variables were collected in systematically laid 109 circular plots each with a 5-m radius (i.e. 31, 41 and 37 plots in the cleared vegetation, plantation and natural forest respectively) in the wet and dry season. We developed behavioural models by correlating the time-budget (i.e. proportion of time vigilance, feeding and moving) of the focal-animals in accordance with habitat variables, group-size and sex-age class. In the wet season, mountain nyala devoted most of their time to vigilance, but they allocated the largest proportion of their time to moving in the dry season. Vigilance differed among the three habitats and was highest in the cleared vegetation during the dry season. Contrary to expectations, adult males were more vigilant than both adult females and sub-adults during the dry season. The behavioural models based on time-budget help to predict how the mountain nyala perceive their environment and trade-off between food acquisition and safety in the wet and dry season. The study also improves our understanding of the adaptive behavioural ecology of the endangered mountain nyala.