DOI: 10.5061/dryad.8qm8r4m
title: Data from: Variations in age- and sex-specific survival rates help explain population trend in a discrete marine mammal population

description: 1. Understanding the drivers underlying fluctuations in the size of animal
 populations is central to ecology, conservation biology and wildlife
 management. Reliable estimates of survival probabilities are key to
 population viability assessments, and patterns of variation in survival
 can help inferring the causal factors behind detected changes in
 population size. 2. We investigated whether variation in age and
 sex-specific survival probabilities could help explain the increasing
 trend in population size detected in a small, discrete population of
 bottlenose dolphins Tursiops truncatus off the east coast of Scotland. 3.
 To estimate annual survival probabilities we applied capture-recapture
 models to photo-identification data collected from 1989 to 2015. We used
 robust design models accounting for temporary emigration to estimate
 juvenile and adult survival, multi-state models to estimate sex-specific
 survival, and age-models to estimate calf survival. 4. We found strong
 support for an increase in juvenile/adult annual survival from 93.1% to
 96.0% over the study period, most likely caused by a change in juvenile
 survival. Examination of sex-specific variation showed weaker support for
 this trend being a result of increasing female survival, which was overall
 higher than for males and animals of unknown sex. Calf survival was lower
 in the first than second year; a bias in estimating third-year survival
 will likely exist in similar studies. There was some support first-born
 calf survival being lower than for calves born subsequently. 5. Coastal
 marine mammal populations are subject to the impacts of environmental
 change, increasing anthropogenic disturbance and the effects of management
 measures. Survival estimates are essential to improve our understanding of
 population dynamics and help predict how future pressures may impact
 populations, but obtaining robust information on the life history of
 long-lived species is challenging. Our study illustrates how knowledge of
 survival can be increased by applying a robust analytical framework to
 photo-identification data.
description: Sighting
 histories_juveniles&adults_Robust Design modelsThis file contains the
 monthly sighting histories of 205 marked juvenile and adult bottlenose
 dolphins sighted off the east coast of Scotland between 1989 and 2015, and
 used to estimate survival rate using a robust design modelling framework.
 The file can be imported into RMark, and then converted to an .inp file to
 fit mark-recapture models (using MARK software). Time intervals (i.e.
 primary and secondary occasions) for robust design analysis are given in
 the file "time.intervals.txt"JuvAd_Robust design
 models.txtSighting
 histories_Sex-specific Juveniles&Adults_Multistate
 modelsThis file contains the
 annual sighting histories of 205 marked juvenile and adult bottlenose
 dolphins sighted off the east coast of Scotland between 1989 and 2015,
 used to estimate sex-specific survival rates using multi-state models.
 Information on sex is provided so that U=unknown, M=male and F=female,
 0=not sighted. The file can be imported into RMark, and then converted to
 an .inp file to fit mark-recapture models (using MARK
 software).JuvAd_Multistate
 models.txtSighting
 histories_calf_age CJS modelsThis file contains the
 annual sighting histories of 56 bottlenose dolphin calves sighted off the
 east coast of Scotland between 1990 and 2015, and used to estimate age
 specific survival rates up to 3 years of age. The sighting histories are
 restricted to calves whose mothers were seen in the three years following
 birth. The file can be imported into RMark, and then converted to an .inp
 file to fit mark-recapture models (using MARK software)
 .calf_age
 CJS models.txtSighting
 histories_adults only_Robust Design modelsThis file contains a
 restricted dataset of only adult bottlenose dolphins, sighted off the east
 coast of Scotland between 1989 and 2015. The monthly sighting histories
 were used to investigate if the detected trend in juvenile&adult
 survival was more likely a change in adult or juvenile survival. The file
 can be imported into RMark, and then converted to an .inp file to fit
 mark-recapture models (using MARK software). Time intervals (i.e. primary
 and secondary occasions) for robust design analysis are given in the file
 "time.intervals.txt"Adult only_Robust design
 models.txtTime intervals for
 Robust Design modelsThis file contains the
 time intervals (primary and secondary occasions) defined for the datasets
 JuvAd_Robust design models.txt and Adult only_Robust design models.txt.
 These time intervals are defined to use in RMark package when fitting
 mark-recapture models.time_intervals.txt