Ecological and anthropogenic covariates ... - GANGAPEDIA

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Discussion One issue that needs to be addressed is the fact that only one side of the gharial is visible at any one time, and that unless both sides are photographed, an individual’s identity remains unknown when presented with only the unrecorded side. However, this can be dealt with by identifying basking sites in advance and positioning oneself before these animals emerge to bask. Thereafter, the sequence of events that accompany most basking episodes provide a way to bypass the issue. Gharials emerge head first onto basking sites, providing an opportunity to ‘capture’ one side and then re-orient themselves so as to face the river. This allows for the other side to be captured too. Other factors that could complicate the implementation of this technique are poor weather conditions, animals lying at odd angles or congregating in a way such that individuals are blocking the observers’ view of other individuals, disturbances that drive basking gharials into the water. Although the use of natural markings is non-invasive and is advantageous over applied tags in specific cases, issues relating to uncertainty in the level of identification, misidentification or misclassification, and unmarkable animals must be considered (Yoshizaki, 2007). Since conventional methods for analysis of capture– recapture data do not account for identification errors, special capture-recapture models that incorporate unmarkable animals (Da Silva et al., 2000, 2003) or models that incorporate the misidentification mechanism (Yoshizaki, 2007; Yoshizaki et al. 2009) will have to be used. Capture-Recapture models provide a statistical framework for estimating p (detection or capture probability) and quantities of biological interest such as population size 57
(Nichols, 1992). Since gharials are individually identifiable (Singh & Bustard, 1976), it may be possible to estimate population sizes by using individual identity within the sampling framework of capture-recapture (Otis et al., 1978). Population studies are essential to determine the status of gharials in the wild, assess the success and validity of conservation measures, make management recommendations and design conservation strategies. To obtain life-history parameters of animals and to be able to determine critical resource requirements, it is essential to monitor individuals for extended periods of time. Identifiable individuals are thus invaluable in the investigation of survival, movement, competition, behavioural strategies and reproductive strategies. Knowledge of the life histories of individual animals used in a new generation of predictive models (Sutherland, 1995) may prove vital to the conservation of those species that are especially vulnerable to human disturbance and for which predictive measures may be of more importance than reactive measures (McGregor & Peake, 1998). Individuals use habitat differently (e.g., Peake, 1997), employ different behavioural strategies (e.g., Rohner, 1996), and have different reproductive success (Newton, 1995); and therefore, individuals should be assumed to have different conservation values unless there is evidence to the contrary (McGregor & Peake, 1998). 58
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Ecological and anthropogenic covari
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variable data like river discharge,
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Table of Contents EXECUTIVE SUMMARY
Page 7 and 8:
In the face of increasing proposals
Page 9 and 10:
Chapter 1 Ecological and Anthropoge
Page 11 and 12: Introduction Humans live disproport
Page 13 and 14: Despite the release of over 5000 yo
Page 15 and 16: its 523 km run, the river passes th
Page 17 and 18: sites considered favourble based on
Page 19 and 20: correction factor for the float mea
Page 21 and 22: Variable (type) Measurement Details
Page 23 and 24: interpolation deriving from regiona
Page 25 and 26: the effects of covariates measured
Page 27 and 28: We compared Zero-Inflated Poisson (
Page 29 and 30: Assessing changes in habitat availa
Page 31 and 32: Figure 6: Box-and-whiskers plots co
Page 33 and 34: Occasion 1: Residual mean deviance
Page 35 and 36: Occasion 3: Residual mean deviance:
Page 37 and 38: Discussion Humans have preferential
Page 39 and 40: Tucker et al. (1997) report that pr
Page 41 and 42: once caught in the net are wary of
Page 43 and 44: Bustard, HR and LAK Singh. 1977. St
Page 45 and 46: Hutton, J. 1989. Movements, home ra
Page 47 and 48: Oliver, M.A., R. Webster. 1990. Kri
Page 49 and 50: Chapter 2 Photographic identificati
Page 51 and 52: Hussain, 2009); and is especially a
Page 53 and 54: data also enables the estimation of
Page 55 and 56: A 600km stretch of the Chambal Rive
Page 57 and 58: Marked animals were accorded no exc
Page 59 and 60: Single-crested region Figure 2: Lat
Page 61: A B C Capture: 07.02.2010 Figure 1.
Page 65 and 66: and Ross, JP. 2007. Gavialis ganget
Page 67 and 68: Mazzoil M., McCulloch S.D., Defran
Page 69 and 70: GENERAL CONCLUSION Humans have pref
Page 71 and 72: APPENDIX - 1 Figure 1: Scatter plot
Page 73 and 74: Figure 2: Scatter plots representin
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