DOI: 10.5061/dryad.bcc2fqzd2
title: Ten year camera trap dataset of tigers in India

description: 1. With continued global changes, such as climate change, biodiversity
 loss and habitat fragmentation, the need for assessment of long-term
 population dynamics and population monitoring of threatened species is
 growing. One powerful way to estimate population size and
 dynamics is through capture-recapture methods. Spatial capture
 (SCR) models for open populations make efficient use of capture-recapture
 data, while being robust to design changes. Relatively few
 studies have implemented open SCR models and to date, very few have
 explored potential issues in defining these models. We develop a series of
 simulation studies to examine the effects of the state space definition
 and between-primary-period movement models on demographic parameter
 estimation. We demonstrate the implications on a 10-year camera-trap study
 of tigers in India. (This is the dataset presented here). 2. The results
 of our simulation study show that movement biases survival estimates in
 open SCR models when little is known about between-primary-period
 movements of animals. The size of the state space delineation can also
 bias the estimates of survival in certain cases. 3. We found that both the
 state space definition and between-primary-period movement specification
 affected survival estimates in the analysis of the tiger dataset
 (posterior mean estimates of survival ranged from 0.71-0.89). 4. In
 general, we suggest that open SCR models can provide an efficient and
 flexible framework for long-term monitoring of populations; however, in
 many cases, realistic modeling of between-primary-period movements is
 crucial for unbiased estimates of survival and density.
description: These data were collected by Wildlife Conservation Society under
 the supervision of Dr. Ullas Karanth and are the joint
 intellectual property of entities, please use proper citations.
 Tiger camera-trap data used in this study come from a study
 implemented in the central part of Nagarahole Reserve, in the state of
 Karnataka, southwestern India. The camera-trap study was initiated in 1991
 and we analyze data from 1991 to 2000, which had previously been analyzed
 using non-spatial capture–recapture models (Karanth et al. 2006). The
 number of camera trap stations used in each year varies from 6 to 80 and
 the sampled area expanded from 41.4km2 to 231.8km2. In addition, the
 sampling duration was reduced from 162 days in 1991 to 30-40 days in the
 later years of the study. There are 10 primary periods over 9 years, thus
 the data are not evenly spaced. Tigers were uniquely identified from the
 photographs. Details concerning the field methods are given in Karanth and
 Nichols (1998) and Table 1 of Karanth et al. (2006) shows the primary
 periods, number of days sampled, the estimated sampled area, the effort in
 trap-nights, and the number of detected individuals. In the original
 analysis of the data set, records of 74 individuals collected over 5725
 trap nights were included. Because data collected in later years allowed
 for the identification of additional individuals, the data set for the
 present analysis contained 75 individuals.
description: Please see the ReadMeTigers.txt file for more details.
 EECam_act.csv: This file contains the number of occasions that
 camera stations were active within a given primary period.
 EERecords.csv: This file contains all of the recorded
 individuals, the trap (camera station), occassion, and year for each time
 the animal was recorded on camera. EEtraplocs.csv: This
 file contains all of the trap (camera station) locations. The x and y are
 centered to remove exact locations within the park, but are still given in
 meters.