Prospecting..?

After a summer in the Alicante region, the Yellow-legged gull "G_1394" came back to its colony the 24th of January. Few days later it returned to Alicante. Is this a prospection or the gull found something wrong with the colony and move to Alicante to breed ?  The prospecting behaviour is still poorly studied but increasing evidence suggests it is more common than previously thought. Stay tuned to know what "G_1394" will do in early spring.

New Publication on Red Kite conservation!

Sergio, F, Tavecchia, G., Blas, J., Taferna, A., Hiraldo, F.  2021. Demographic modeling to fine‐tune conservation targets: importance of pre‐adults for the decline of an endangered raptor. Ecological Applications, https://doi.org/10.1002/eap.2266

Summary: Large, long‐lived species with slow life histories and protracted pre‐breeding stages are particularly susceptible to declines and extinction, often for unknown causes. Here, we show how demographic modeling of a medium‐sized raptor, the Red Kite Milvus milvus, can aid to refocus conservation research and attention on the most likely mechanisms driving its decline. Red Kites’ survival and reproduction increased through three sequential stages for 1–2, 3–6, and 7–30 yr of age, mainly corresponding to individuals that are dispersing, attempting to gain a territory, and breeding. As typical of long‐lived species, elasticities were highest for adult (≥7 yr old) survival, but this was high, with little scope for improvement. Instead, the declines were driven by an extremely low survival of pre‐adults in their first years of life, which weakened the whole demographic system by nullifying the offspring contribution of adults and curtailing their replacement by recruits. For example, 27 pairs were necessary to generate a single prime age adult. Simulation of management scenarios suggested that the decline could be halted most parsimoniously by increasing pre‐adult survival to the mean levels recorded for other areas, while only the synergistic, simultaneous improvement of breeding success, adult and pre‐adult survival could generate a recovery. We propose three actions to attain such goals through selective supplementary feeding of both breeding and non‐breeding individuals, and through mortality improvement by GPS remote‐sensing devices employed as surveillance monitoring tools. Our results show how improving demographic models by using real, local vital rates rather than “best guess” vital rates can dramatically improve model realism by refocusing attention on the actual stages and mortality causes in need of manipulation, thus building precious time and resources for conservation management. These results also highlight the frequent key role of pre‐adult survival for the management of long‐lived species, coherent with the idea of demographic systems as integrated chains only as strong as their weakest link.

 

 

 

New Publication on Urban Ecology!

Luna, Á., Lois, N.A., Rodríguez-Martinez, S., Palma, A., Sanz-Aguilar, A., Tella, J. L. Carrete, M.. 2021 Urban life promotes delayed dispersal and family living in a non-social bird species. Scientific Report 11, 107 (2021). https://doi.org/10.1038/s41598-020-80344-8

Abstract. In some vertebrate species, family units are typically formed when sexually mature individuals delay dispersal and independent breeding to remain as subordinates in a breeding group. This behaviour has been intensively studied in gregarious species but has also been described in non-social species where ecological and evolutionary drivers are less known.

Photo: N. Rebolo

Here, we explore factors that favour delayed dispersal and family living and potential benefits associated with this strategy in a non-social, monogamous species (the burrowing owl, Athene cunicularia) occupying urban and rural habitats. Our results show that family units arise when first-year individuals, mainly males, delay their dispersal to stay in their natal nests with their parents. This delayed dispersal, while still uncommon, was more prevalent in urban (7%) than in rural (3%) habitats, and in areas with high conspecific density and productivity. Birds delaying dispersal contributed to the genetic pool of the offspring in 25% of the families analysed, but did not increase the productivity of the nests where they remained. However, their presence was related to an improvement in the body condition of chicks, which was ultimately linked to a slightly positive effect in offspring future survival probabilities. Finally, delayed dispersers were recruited as breeders in high-quality urban territories and closer to their natal nests than individuals dispersing during their first year of life. Thus, our results suggest that delaying dispersal may be mainly related to opportunities to inheriting a good quality territory, especially for males. Our study contributes to understanding the role played by habitat quality in promoting delayed dispersal and family living, not only in social but also non-social species, highlighting its impact in the ecology and evolution of animal populations.