Conservation Genetics

, Volume 11, Issue 6, pp 2299–2310

Addressing challenges in non invasive capture-recapture based estimates of small populations: a pilot study on the Apennine brown bear

  • V. Gervasi
  • P. Ciucci
  • F. Davoli
  • J. Boulanger
  • L. Boitani
  • E. Randi
Research Article

DOI: 10.1007/s10592-010-0115-7

Cite this article as:
Gervasi, V., Ciucci, P., Davoli, F. et al. Conserv Genet (2010) 11: 2299. doi:10.1007/s10592-010-0115-7

Abstract

It is often difficult to determine optimal sampling design for non-invasive genetic sampling, especially when dealing with rare or elusive species depleted of genetic diversity. To address this problem, we ran a hair-snag pilot study on the remnant Apennine brown bear population. We used occupancy models to estimate the performance of an improved field protocol, a meta-analysis approach to indirectly model capture probability, and simulations to evaluate the effect of genotyping errors on the accuracy of capture-recapture population estimates. In spring 2007 we collected 70 bear hair samples in 15 5 × 5 km cells, using 5 10-day trapping sessions. Bear detectability was higher in 2007 than in a previous attempt on the same population in 2004, reflecting improved field protocols and sampling design. However, individual capture probability was 0.136 (95% CI = 0.120–0.152), still below the minimum requirements of capture-mark-recapture closed population models. We genotyped hair samples (n = 63) at 9 microsatellite loci, obtaining 94% Polymerase Chain Reaction success, and 13 bear genotypes. Estimated PIDsib was 0.00594, and per-genotype error rate was 0.13, corresponding to a 99% probability of correct individual identification. Simulation studies showed that the effect of non-corrected or filtered genetic errors on the accuracy of population estimates was negligible only when individual capture probability was >0.2. Our results underline how the interaction among field protocols, sampling strategies and genotyping errors may affect the accuracy of DNA-based estimates of small and genetically depleted populations, and warned us about the feasibility of a survey using only traditional hair-snag sampling. In this and similar cases, indications from pilot studies can provide cost-effective means to evaluate the efficiency of designed sampling and modelling procedures.

Keywords

Apennine brown bearCapture-mark-recaptureDNA samplingGenotyping errorOccupancy modelsPilot study

Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  • V. Gervasi
    • 1
  • P. Ciucci
    • 1
  • F. Davoli
    • 2
  • J. Boulanger
    • 3
  • L. Boitani
    • 1
  • E. Randi
    • 2
  1. 1.Dipartimento di Biologia Animale e dell’UomoUniversità “La Sapienza” di RomaRomeItaly
  2. 2.Istituto Nazionale per la Fauna SelvaticaOzzano EmiliaItaly
  3. 3.Integrated Ecological ResearchNelsonCanada