miércoles, 27 de septiembre de 2017

New Publication on the multidimensional value of long-term studies !

Tavecchia, G., Oro, D., Sanz-Aguilar, A., and Béchet, A. 2017. The multidimensional value of long-term individual.based studies: more than lots of data. Avocetta 41: 19-21


With the present rate of biodiversity loss and the profound effects of global changes, population and conservation ecologists face new questions. Many of these are related to how fast individuals can adapt to the strength and pace of environmental variability and can only be answered using individual data collected over long-term (Long Terms Individual Based Studies). Beside this undoubted scientific value, a 20 – 30 years study is likely to have trained several generations of scientists, fostered collaborations between a large number of research institutes and promoted public awareness on scientific themes and wildlife conservation problems. With current public systems providing funds for 3 to 4 years, it is increasingly difficult to initiate and maintain a long-term individual based study. As a consequence, many field studies end before time, without reaching the number of years or the amount of data needed to meet current scientific challenges and to demonstrate their educational value.Here, we argue that the value of LTIBS is multidimensional and it grows steadily with time. How and when does a long-term field study become important? [..] continue reading here






This text is in honor of Dr. Alan Roy Johnson (1941-2014, Photo), Dr. Heinz Hafner (1940-2003) and other pioneers of LTIBS. By focusing the attention on the multidimensional value of LTIBS we aimed to pay a tribute to them and to those people who, thanks to their passion, personal sacrifices and tenacity are keeping these projects alive.
 

A. Johnson (photo. H. Hôte)

lunes, 25 de septiembre de 2017

Visiting GEP

Dr. L. Corlatti is visiting the GEP for few weeks. Luca will work with G. Tavecchia and A. Sanz-Aguilar on estimating mortality of deers at the Stelvio National Park using radio-tracking data. 

viernes, 22 de septiembre de 2017

Ph.D. Defense!

Noelia Hernandez Muñoz defended successfully her Ph.D. titled "Effects of environmental stochasticity on life history parameters of marine top predators" supervised by Prof. D. Oro.   Well done Noelia !


You can find Noelia's published work here

domingo, 17 de septiembre de 2017

New publication on Tiger Mosquito range expansion !

Tavecchia, G., Miranda, M.-A., Borrás, D., Bengoa, M., Barceló, C. Paredes-Esquivel, C. and Schwarz, C. 2017 Modelling the range expansion of the Tiger mosquito in a Mediterranean Island accounting for imperfect detection   Frontiers in Zoology, 14:39-49 doi. 10.1186/s12983-017-0217-x

Abstract: Aedes albopictus (Diptera; Culicidae) is a highly invasive mosquito species and a competent vector of several arboviral diseases that have spread rapidly throughout the world. Prevalence and patterns of dispersal of the mosquito are of central importance for an effective control of the species. We used site-occupancy models accounting for false negative detections to estimate the prevalence, the turnover, the movement pattern and the growth rate in the number of sites occupied by the mosquito in 17 localities throughout Mallorca Island. Site-occupancy probability increased from 0.35 in the 2012, year of first reported observation of the species, to 0.89 in 2015. Despite a steady increase in mosquito presence, the extinction probability was generally high indicating a high turnover in the occupied sites. We considered two site-dependent covariates, namely the distance from the point of first observation and the estimated yearly occupancy rate in the neighborhood, as predicted by diffusion models. Results suggested that mosquito distribution during the first year was consistent with what predicted by simple diffusion models, but was not consistent with the diffusion model in subsequent years when it was similar to those expected from leapfrog dispersal events. Assuming a single initial colonization event, the spread of Ae. albopictus in Mallorca followed two distinct phases, an early one consistent with diffusion movements and a second consistent with long distance, ‘leapfrog’, movements. The colonization of the island was fast, with ~90% of the sites estimated to be occupied 3 years after the colonization. The fast spread was likely to have occurred through vectors related to human mobility such as cars or other vehicles. Surveillance and management actions near the introduction point would only be effective during the early steps of the colonization.


viernes, 15 de septiembre de 2017

Gull tracking on the news (2) !

José Manuel Igual speaks about the Yellow-Legged Gull study at Dragonera Natural Park to the "Mallorca Zeitung" (text in German).


lunes, 11 de septiembre de 2017

New publication on Storm Petrel population dynamics !

 Population Ecology, 59:225–238, doi: 10.1007/s10144-017-0590-5
 
Photo By A. Caldas (Flickr)
Abstract : Life-history traits of migratory seabirds are influenced by changing conditions at breeding and wintering grounds. Climatic conditions and predation are known to impact populations’ survival rates, but few studies examine their effect simultaneously. We used multievent capture–recapture models to assess mortality due to environmental conditions and predation in breeding European storm petrels (Hydrobates pelagicus) in two allopatriccolonies  (Mediterranean and Atlantic). Predatory mortality at the colonies showed annual variation, being around 0.05 in certain years. Mortality at sea differed between the two oceanic basins, and was lower in the Mediterranean colony [0.11, 95% CI (0.09, 0.14)] when compared to the Atlantic colony [0.18, 95% CI (0.15, 0.22)]. The Western Mediterranean Oscillation index (WeMOi)  explained 57%of the temporal variability in mortality of Mediterranean breeders. In comparison, 43% of the temporal variability in mortality of Atlantic breeders was explained by the winter St Helena index (wHIX) and El Niño-Southern Oscillation index (wENSO). Our results suggest that Mediterraneanbreeders remain in this basin for wintering where they may face lower migratory costs and more favourable environmental conditions. In contrast, Atlantic breeders’ mortality may be due to higher cost of migration, changing upwelling conditions in the Benguela current  and heavy storms over their migratory route during La Niña events. This study underlines the importance of modelling separately different causes of mortality when testing the effects of climatic covariates.
 

martes, 1 de agosto de 2017

New Publication on Ferreret, the Majorcan midwife toad !


Pinya, S., Tavecchia,G. and Valentín Pérez-Mellado, V. Population model of an endangered amphibian: implications for conservation management  Endangered Species Research, 34: 123–130, doi.org/10.3354/esr00835

From Wikipedia.com
Abstract: Amphibian populations are declining worldwide, but for many taxa, robust estimates
of demographic parameters to assess population state or trends are scarce or absent.
robust estimates of adult apparent survival of the endemic Majorcan midwife toad Alytes muletensis using individual capture-recapture data collected over 4 yr in a 60 m2 cistern. Moreover, we combined the vital rates into a stage-structured population model to estimate the ex pected longterm growth rate of the population. Apparent survival estimates of males and females were similar (0.737 ± 0.042 and 0.726 ± 0.045, respectively) indicating that the egg-carrying behavior of males, typical of this species, does not reduce its survival probability. We found evidence of a low local survival of juveniles compared with adults, most likely due to permanent dispersal. Adult population size estimation provided higher tadpole:adult ratios than previously reported for this endangered species, suggesting an overestimation of the previous adult population size. Model projections suggested a stable population, since λ, the expected asymptotic growth rate of the population, was close to 1.00.

Full text here