Spring 2016 campaign on Lilford's lizard ended!

The 2016 spring campaign on Lilford's lizard ended last week. It has been a difficult one, with many days of bad weather and several unexpected problems with boat and logisitc....but hey, this is job. Populations reached a very low level, but it seems there will be many new recruits in October. Thank to the many people from the GEP who gave their help.

New publication on spring population dynamics of lizards

Pérez-Mellado, V., Garcia-Diez, T., Hernández-Estévez, J.A. & Tavecchia, G. : Behavioural processes, ephemeral resources and spring population dynamics of an insular lizard, Podarcis lilfordi (Squamata: Lacertidae). Italian Journal of Zoology doi: 10.1080/11250003.2015.1093035


Abstract: Temporal changes in adult sex ratio of animal populations might be due to differences in movements, survival or detection probabilities. We used data from an intensive capture–mark–recapture study of 720 lizards at the islet of Aire (Balearic Islands, Spain) to investigate the demographic mechanisms underlying the spring uneven sex ratio. We simultaneously estimated survival (f), the proportion of transient animals (p) and the probability of recapture (p) of lizards at the study plot.

Photo: G. Tavecchia

We then estimated population size using open population models for individually based data and compared these with the observed values. Results indicated that males had a higher probability of recapture than females, but this was not sufficient to generate the observed male-biased sex ratio. The proportion of transient males decreased at the end of spring in parallel with the end of the blooming period of the dead horse arum, Helicodiceros muscivorus, a short-lasting food and thermoregulation resource for lizards during spring. Changes in the proportion of transients suggested that sex-dependent movements, most likely linked to a monopolising behaviour of this plant resource, were responsible for the observed difference in the number of males and females. Our results reveal how the interplay of behavioural and ecological factors explains short-term changes in population dynamics and shapes the movement patterns within the island.

New publication on photo-identification

Moya, Ó., Mansilla, P.-L., Madrazo, S., Igual, J.-M., Rotger, A., Romano, A. and Tavecchia G. APHIS: A new software for photo-matching in ecological studies  Ecological Informatics 2015 doi:10.1016/j.ecoinf.2015.03.003

Abstract: Unique body characteristics are increasingly used for individual recognition to avoid the effort and the potential negative effects of capture–mark–recapture technique. 
As a consequence there is a growing demand for computer procedures to assist users in photo-recognition of an individual. We present a new software for photo-matching developed to minimize the pre-processing time and maximize the speed of the matching procedure. In APHIS photos can be processed in batches of hundreds and users can select between two alternative matching procedures, one interactive, built as an extension of existing and freely available software, and one automatic. We assessed its performance in terms of individual recognition and time efficiency and illustrate its use with real capture-photo–recapture studies on a reptile and an amphibian species, the Balearic Lizard Podiarcis lilfordi and the Northern spectacled salamander Salamandrina perspicillata, with contrasting skin patterns.

You can download APHIS here

Lizards

The Lizard 2015 Spring Campaign has started

Nearly done

Lizard October campaign is coming to an end with only two more days to go. Thank to Pelopantón we have a pic of our biological station (above). Yep! It's a tough job in an hostile environment .. but hey, someone has to do it !

Lizards!

The October fieldwork campaign had began!