New Publication on the role of dispersal in animal populations

Tavecchia, G., Tenan, S., Pradel, R., Igual, J.-M., Genovart, M. and Oro, D. 2016 : Climatic-driven vital rates do not always mean climate-driven population. Global Change Biology. doi10.1111/gcb.13330

Abstract: Current climatic changes have increased the need to forecast population responses to climate variability. A common approach to address this question is through models that project current population state using the functional relationship between demographic rates and climatic variables. We argue that this approach can lead to erroneous conclusions when interpopulation dispersal is not considered. We found that immigration can release the population from climate-driven trajectories even when local vital rates are climate dependent. We illustrated this using individual-based data on a trans-equatorial migratory seabird, the Scopoli's shearwater Calonectris diomedea, in which the variation of vital rates has been associated with large-scale climatic indices. We compared the population annual growth rate λ_i, estimated using local climate-driven parameters with ρ_i, a population growth rate directly estimated from individual information and that accounts for immigration. While λ_i varied as a function of climatic variables, reflecting the climate-dependent parameters, ρ_i did not, indicating that dispersal decouples the relationship between population growth and climate variables from that between climatic variables and vital rates. Our results suggest caution when assessing demographic effects of climatic variability especially in open populations for very mobile organisms such as fish, marine mammals, bats, or birds. When a population model cannot be validated or it is not detailed enough, ignoring immigration might lead to misleading climate-driven projections.

GEP on Media

The publication by M. Genovart on Balearic Shearwaters has reached the media !

Here a short television interview (Chapter 43/1, at min 24).  

A press release (in Spanish) here and a short note by the BBC Science & Environment here

New publication on Lesser kestrel demography in Sicily!

Di Maggio, R., Campobello, D., Tavecchia, G. and Sará M. 2016: Habitat- and density-dependent demography of a colonial raptor in Mediterranean agro-ecosystems  Biological Conservation, vol 193 pag 116-123. doi:10.1016/j.biocon.2015.11.016

Abstract: Agricultural intensification is considered the major cause of decline in farmland bird populations, especially in the Mediterranean region. Food shortage increased by the interaction between agricultural intensification and density-dependent mechanisms could influence the population dynamics of colonial birds. We used demographic data on lesser kestrels (Falco naumanni), a key species of Mediterranean pseudo-steppes, to understand the importance of land-use changes and density-dependent mechanisms in the light of its fluctuating conservation status in the Western Palearctic. Our analysis indicated an important influence of land uses (artichokes, arable and grassland fields) and colony size on kestrel survival rates.

The strong habitat effect revealed the unsuitability of intensive arable lands with respect to extensive grasslands for lesser kestrels. Notably, artichokes, a winter-intensive crop, proved to be a high-quality habitat as they were associated with survival values equal to those of grassland. This is likely due to prey availability and reveals that non-traditional crops may provide suitable habitats for lesser kestrels. Information theory gave strong support to the negative influence of colony size on fecundity, albeit a small one, for its positive effect on survival probability. The estimated population growth rate was negative for all three habitats, indicating a decline over time and urging conservation actions in all of the areas studied. This decline was much higher in colonies surrounded by arable fields. In sensitivity analyses, λ indicated that adult survival was the parameter with the greatest effect on population growth, followed by survival of fledglings and fecundity. Our study showed how the costs and benefits of group living interact with agricultural intensification to drive species demography. In addition, we integrated significant information on one of the largest lesser kestrel populations to fine tune the most effective conservation strategy to prevent the collapse of the species in a relevant part of its range

The 2015 Introductory Course on CMRR analysis has ended: see you next year!

The 2015 Introductory Course on CMRR analysis has ended last friday. Thanks to all participants. We had the opportunity to learn about Oryx and Wolves, Cormorants, Bears, Butterflies, Small mammals, Woodcocks, about hunting, conservations and wind farms.  It has been the opportunity to address scientific questions and, on top of all, to meet nice people.  Thank you again.

Debating about GOF and AIC, of course (apologises for the missing persons, it is the only pic I have)

See you next year, last week of November, as always.

Kick-off meeting of the EU-project MINOUW

 Palma, 13-16 April 2015

 The GEP is involved in estimating the effect of discard reduction on seabird population dynamics

Weekly Seminar on Thursday

Thursday 19th of March, at 11h00 in the Seminar Room,  Dr. Pilar Santidrian will talk about her work on leatherback turtles in Costa Rica   "Eastern Pacific leatherback turtles face extinction". 
See you there !!

GEP at Boulder University

Meritxell Genovart and Daniel Oro are visiting the University of Boulder (Colorado, USA) for three months.Their collaboration with Prof D. Doak will certainly bring exciting results in the field of population dynamics. We will keep you posted.

New Publication on population dynamics of trouts in Asturia

Férnandez-Chacón, A., Genovart, M., Álvares, D.,Cano, J.M, Ojanguren, A.F., Rodriguez-Muñoz, R.,Nicieza, A.G. Neighbouring populations, opposite dyanmics: influence of body size and environmental variation on the demography of stream-resident brown trout (Salmo trutta). Oecologia 

In organisms such as fish, where body size is considered an important state variable for the study of their population dynamics, size-specific growth and survival rates can be influenced by local variation in both biotic and abiotic factors, but few studies have evaluated the complex relationships between environmental variability and size-dependent processes. We analysed a 6-year capture–recapture dataset of brown trout (Salmo trutta) collected at 3 neighbouring but heterogeneous mountain streams in northern Spain with the aim of investigating the factors shaping the dynamics of local populations. The influence of body size and water temperature on survival and individual growth was assessed under a multi-state modelling framework, an extension of classical capture–recapture models that considers the state (i.e. body size) of the individual in each capture occasion and allows us to obtain state-specific demographic rates and link them to continuous environmental variables. Individual survival and growth patterns varied over space and time, and evidence of size-dependent survival was found in all but the smallest stream. At this stream, the probability of reaching larger sizes was lower compared to the other wider and deeper streams. Water temperature variables performed better in the modelling of the highest-altitude population, explaining over a 99 % of the variability in maturation transitions and survival of large fish. The relationships between body size, temperature and fitness components found in this study highlight the utility of multi-state approaches to investigate small-scale demographic processes in heterogeneous environments, and to provide reliable ecological knowledge for management purposes.