Assessing dog population management using the robust design mark-recapture method

Abstract

Poster for UFAW conference 2019
"Advancing animal welfare science: How do we get there? - Who is it good for?"

Full text

Assessing dog population management using the robust
design mark-recapture method
*LM Smitha, S Hartmannb, A Munteanub, P Dalla Villac, R Quinnella, LM Collinsa
aFaculty of Biological Sciences, University of Leeds (UK), bVIER PFOTEN International
and cIstituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “G. Caporale” (IT).
*bslsmi@leeds.ac.uk
Robust design mark-recapture method
•Count the number of dogs observed on a survey route (individually identifying by photographs).
•Primary sampling occasions occur over two weeks every three months in four study areas in both Lviv and Pescara (excluding winter).
•Study areas are surveyed three times over three consecutive days (secondary sampling period) (figure 2).
•Estimate capture probability –the probability of observing a dog if present in the population.
•Use the capture probability to estimate demographic parameters for the population.
Implications and future work
•Simple counts or mark-recapture methods fail to consider the influences of dog
movement, reproduction or mortality.
•Parameters will be estimated for recruitment and removal in Lviv (Ukraine) and
Pescara (Italy) and related to the dog population management methods in the local
area.
•This information will be incorporated into a systems model to assess the overall
effectiveness, efficiency and sustainability of dog population management methods.
Background & study aim
•Domestic dog population size is ~700 million. 75% are free-roaming. Concern for: animal welfare,
public health & wildlife.
•Populations are managed through: culling, fertility control and sheltering.
•The impact of dog population management is often evaluated by their effect on dog population
size, commonly estimated using mark-recapture methods that do not consider the recruitment or
removal processes of the population1(figure 1).
•This information helps in identifying the dominant factors that maintain or change the dog
population size, which has implications for the efficacy of dog population management methods.
•Study aim: Estimate recruitment and removal rates for dog populations in Lviv (Ukraine) and
Pescara (Italy) using robust design mark-recapture.
References:
1. Belo VS, Werneck GL, da Silva ES, Barbosa DS, Struchiner CJ (2015) Population Estimation Methods for Free-Ranging Dogs: A
Systematic Review. PLoS ONE 10(12): e0144830. doi:10.1371/journal.pone.0144830
Three surveys over
consecutive days
(population closed to
influences)
Closed mark-recapture
Day 3
•One sampling occasion with three surveys over 3 days (can
be repeated and compared).
•Assumes closed population geographically (no movement
into our out of study area) and demographically (no births
or deaths).
•Can be used to estimate:
oPopulation size
Robust design mark-recapture
•Multiple primary sampling occasions with three secondary
sampling occasions over 3 days.
•Uses a mixture of open (between primary sampling
occasions) and closed population design (between
secondary sampling occasions).
•Can be used to estimate:
oPopulation size
oRecruitment –birth rate, abandonment rate,
immigration.
oRemoval –death rate, adoption rate and emigration.
Day
1
Day
2
Day
3
Day
1
Day
2
Day
3
Day
1
Day
2
Day
3
Primary sampling occasions (open to
demographic and geographic influences)
Secondary
sampling occasions
(closed to
influences)
Xnumber of days months or years in
between primary sampling occasions
Day 2
Day 1
Figure. 2. Robust design mark-recapture study design, illustrating “open population” primary sampling occasions and “closed
population” secondary sampling occasions.
Figure. 1. Closed mark-recapture study design.