Showing posts with label tag loss. Show all posts
Showing posts with label tag loss. Show all posts

Tuesday, 12 May 2020

New Publication on Lapped-faced vulture !

Santangeli A., Pakanen, V-M, Bridgeford, P., Boorman, M., Kolberg, H., and Sanz-Aguilar, A. 2020. The relative contribution of camera trap technology and citizen science for estimating survival of an endangered African vulture. Biological Conservation, vol, 246 https://doi.org/10.1016/j.biocon.2020.108593

Photo:wikipedia.org
Abstract: Technological advances such as camera traps, and citizen science, coupled with advanced quantitative approaches, can help fill existing knowledge gaps and aid effective conservation. We combine citizen and camera trap observations to estimate survival of the Endangered lappet-faced vulture, assess the relative contribution of data from camera traps and citizens, as well as impact of loss of individual marks (wing tags), on survival estimates.  We used data from 762 lappet-faced vultures wing tagged as nestlings during 2006-2017 in western Namibia. Observations of wing tagged individuals were provided by citizens or via camera traps.
We formulated a multievent capture-mark-recapture model to estimate survival while accounting for probabilities of resighting by citizens and/or camera traps, recovery of dead individuals, and loss of the wing tag.  Survival was relatively high for juveniles (0.79), and increased with age to 0.95. Citizen observations of live and dead birds were low in number. However, when combined with camera trap resightings of live individuals, citizen observations increased the precision of survival estimates of birds older than one year compared to using data from either sources separately. Wing tag loss was high after 5–6 years of tag age. If neglected, tag loss can result in severe underestimation of survival of the older age classes. Overall, we show that filling ecological knowledge gaps is possible through the efficient use of data provided by different sources, and by applying state-of the art approaches that minimise potential biases, such as those due to tag loss.

Friday, 14 June 2019

New Publication on poaching related mortality !

Corlatti, L., Sanz-Aguilar, A., Tavecchia, G., Giugiatti A., and Pedrotti, L., 2019 Unrevelling the sex- and age-specific impact of poaching mortality with multievent modeling Frontiers in Zoology, https://doi.org/10.1186/s12983-019-0321-1

Abstract:  Poaching is a prominent source of ‘hidden hurdles’, cryptic impacts of human activities that may hinder the conservation of animal populations. Estimating poaching mortality is challenging, as the evidence for illegal killing is not outwardly obvious. Using resighting and recovery data collected on 141 marked red deer Cervus elaphus within the Stelvio National Park (central Italian Alps), we show how multievent models allow to assess the direct impacts of illegal harvesting on age- and sex-specific survival, accounting for uncertainty over mortality causes.

Mortality caused by poaching was consistently higher for males than for females in all age classes. In males, the probability of dying from poaching was higher for extreme age classes, while in females all age classes showed fairly similar values of poaching mortality. The strong bias in sex-specific poaching mortality was possibly due to trophy killing in adult males and ‘bushmeat-like’ killing for private or commercial gain in young males and in females.

A robust assessment of age- and sex-specific prevalence of poaching in wildlife populations is pivotal when illegal killing is of conservation concern. This provides timely information on what segment of the population is most likely to be affected. Besides obvious demographic consequences on small populations, age- and sex-biased poaching prevalence may contrast with the need to maintain ecosystem complexity and may alter behavioral responses to human presence. The information provided by multievent models, whose flexibility makes them adaptable to many systems where individual-based data is part of population monitoring, offers a support to design appropriate strategies for the conservation of wildlife populations.

Wednesday, 20 February 2019

New Publication on Egyptian vulture and EU-LIFE project !


Badia‐Boher, J., Sanz-Aguilar A., de La Riva M., Gangoso, L., van Overveld, T., García-Alfonso, M., Luzardo, O. P,Suarez Pérez, A., and  Donázar, J. A. 2019 Evaluating European LIFE conservation projects: Improvements in survival of an endangered vulture. Journal of Applied Ecology, doi 10.1111/1365-2664.13350.
  1. Long‐lived avian scavengers are threatened worldwide and thus, are common targets of conservation plans. However, scientific evidence of both the factors limiting populations and effectiveness of management actions are greatly needed in order to develop more efficient and successful conservation strategies.
  2. We assessed the effectiveness of conservation actions applied within a LIFE‐Nature project aimed at improving the long‐term survival of the critically endangered Canarian Egyptian vulture: including education campaigns for public awareness and control of illegal poisoning and the modification of power lines to reduce the risk of accidents. We formulated a multievent capture–mark–recapture model to obtain estimates of survival for juvenile, subadult and adult birds accounting for probabilities of resight, recovery and losses of metal and colour rings.
  3. Models supported a substantial enhancement in survival for subadult and adult birds and a moderate improvement for juveniles after the implementation of LIFE actions. Ring loss probabilities became notably high in the middle to long term.
  4. Poisoning events became very rare after LIFE was implemented, suggesting a positive effect of environmental education and awareness campaigns. Entanglements and collisions in power lines were also efficiently mitigated. Instead, electrocutions became the most identified cause of death in the post‐LIFE stage.
  5. Synthesis and applications. Our results highlight the improvement of survival in a threatened island vulture population after the implementation of a European LIFE conservation project. On small islands, with small human populations and few stakeholders, education and awareness campaigns can be especially effective for biodiversity conservation. We also demonstrate the need to complement conservation programmes with long‐term monitoring, which is essential to evaluate the effectiveness of actions, especially for long‐lived species
Press notes here and here.

Subscriptions to CMRR 2026 workshop open!

Subscription to the upcoming workshop on CMRR analysis, now open.  INTRODUCTORY COURSE : 23 - 27 Nov. 2026, Mallorca, Spain     (places: 20,...