Data from: Implications of survey effort on estimating demographic parameters of a long-lived marine top predator

Effective management of wildlife populations rely on knowledge of their
abundance, survival and reproductive rates. Maintaining long-term studies
capable of estimating demographic parameters for long-lived, slow
reproducing species is challenging. Insights into effects of research
intensity on the statistical power to estimate demographic parameters is
limited. Here, we investigate implications of survey effort on estimating
abundance, home range sizes and reproductive output of Indo-Pacific
bottlenose dolphins (Tursiops aduncus), using a three-year sub-sample of a
long-term, capture-recapture study off Bunbury, Western Australia.
Photo-identification on individual dolphins were collected following
Pollock’s Robust Design, where seasons were defined as ‘primary periods’,
each consisting of multiple ‘secondary periods’. The full dataset
consisted of 12 primary periods and 72 secondary periods, resulting in the
study area being surveyed 24 times/year. We simulated reduced survey
effort by randomly removing one, two or three secondary periods per
primary period. Capture-recapture models were used to assess the effect of
survey intensity on the power to detect trends in population abundance,
while individual dolphin sighting histories were used to assess the
ability to conduct home range analyses. We used sighting records of adult
females and their calving histories to assess survey effort on quantifying
reproductive output. A 50% reduction in survey effort resulted in: i) up
to a 36% decline in population abundance at the time of detection; ii) a
reduced ability to estimate home range sizes, by increasing the time for
individuals to be sighted on >30 occasions (an often-used metric
for home range analyses) from 7.74 to 15.46 years; and iii) 33%, 24% and
33% of annual calving events going undocumented in their year of birth.
Results clearly illustrate the importance of survey effort on the ability
to assess demographic parameters with clear implications for population
viability analyses, population forecasting and conservation efforts to
manage human-wildlife interactions.

Capture history
dataThis data file contains
the capture histories of 229 individuals over a 3 year period. Data was
collected using photo-identification methods with survey design to fit the
Robust design. Each row is an individual, while each column is a secondary
period. There were six secondary periods collected per primary period.
Data were collected over 12 primary periods (australasian seasons)
resulting in 72 total secondary periods.dryad1.txtCalving event dataThis data contains the 100 known females and any sightings of their respective calves (if any). The dataset consisted of 12 primary periods (australasian seasons), with 4 primary periods collected for each of 3 years. Calf code is a unique identifier for each individual calf.dryad2.txt