Papers by Albert Bertolero
bioRxiv (Cold Spring Harbor Laboratory), Jun 28, 2019
1. Understanding the behaviour of a population under perturbations is crucial and can help to mit... more 1. Understanding the behaviour of a population under perturbations is crucial and can help to mitigate the effects of global change. Sociality can influence the dynamics of behavioural processes and plays an important role on populations' resilience. However little is known about the effects of perturbations on the social cohesion of group-living animals. 2. To explore the strength of social cohesion and its dynamics under perturbations, we studied an ecological system involving a colonial, long-lived species living in a site experiencing a shift to a perturbed regime. This regime, caused by the invasion of predators, led this colony to hold from 70% to only 3% of the total. CC-BY-NC-ND 4.
Butlletí del Grup Català d'Anellament, 1992
A Reed Bunting with an extra secondary in the right wing was captured on 0 1.02.92 at Canal Vell ... more A Reed Bunting with an extra secondary in the right wing was captured on 0 1.02.92 at Canal Vell (Deltebre, Tarragona). This extra secondary was heavily abraded and was unharmoniously situated between the fifth and the sixth secondaries. The most probable explanation for this feather was that it could be a "one off", produced during juvenile development with no ensheathed tip of the next feather generation at the base of the calamus.
Proceedings of The Royal Society B: Biological Sciences, Apr 27, 2016
Conditions during early life, including maternal cohort effects, can influence the future fitness... more Conditions during early life, including maternal cohort effects, can influence the future fitness of individuals. This may be particularly true for longdistance migrating birds, because, apart from conditions experienced by cohorts during rearing, conditions during early life in regions far from breeding grounds may also influence their population dynamics. Very little is known about the fitness consequences of those conditions experienced by juveniles after independence, especially in wild populations and for longlived birds. We used multi-event capture-recapture-recovery models and a unique 26-year dataset for the Audouin's gull (Larus audouinii) to assess for the first time whether survival was influenced by early conditions, both during the rearing period (i.e. a maternal cohort effect potentially affected by density dependence) and the first winter (i.e. a cohort effect driven by climate when birds disperse to wintering grounds). Our results show that juvenile survival was highly sensitive to early-life conditions and that survival decreased with stronger density dependence and harsh climate. The two consecutive cohort effects were of similar magnitude and they may represent a selection filter. Thus, early-life conditions had a strong impact on survival, and neglecting this complexity may hinder our understanding on how populations of long-lived animals fluctuate and respond to perturbations.
Biblioteca de la Universidad Complutense de Madrid, Base de datos de artículos de revistas, ...
Ringing and Migration, Dec 1, 1995
ABSTRACT The primary moult of Curlew Sandpiper Calidris ferruginea was studied at a staging area ... more ABSTRACT The primary moult of Curlew Sandpiper Calidris ferruginea was studied at a staging area in the south of Europe. The duration of primary moult was estimated as 73 days (9 August to 21 October), a shorter period than those reported in the wintering areas. Birds in moult showed a lower speed of fat accumulation than non moulters. An increase in the proportion of moulting birds was detected at the end of the migratory period, probably as a result of a longer staging time of moulting birds in the study area. The number and sex‐ratio of birds in wing moult showed a great annual variation. The brooding system of this species, in which only females give parental care, and the great annual variation in breeding success could be two of the factors that explain the great yearly variation in the moult schedule of Curlew Sandpiper.
Waterbirds, Dec 1, 2008
Abstract The Peruvian Tern (Sternula lorata) is one of the rarest seabirds that breed on the barr... more Abstract The Peruvian Tern (Sternula lorata) is one of the rarest seabirds that breed on the barren desert plains of Peru and Chile. Unlike the majority of seabirds breeding in this region, Peruvian Terns nest in open areas on the mainland, where they are exposed to ...
Proceedings of The Royal Society B: Biological Sciences, Oct 19, 2022
Agricultural policies against invasive species generate contrasting outcomes for climate change m... more Agricultural policies against invasive species generate contrasting outcomes for climate change mitigation and biodiversity conservation.
Ornitologia Neotropical, Nov 28, 2008
Aquatic Conservation-marine and Freshwater Ecosystems, Jun 11, 2018
Bird Study, Nov 1, 1998
... does not give any warranty express or implied or make any representation that the contents wi... more ... does not give any warranty express or implied or make any representation that the contents will be ... 41.Figuerola, J. & Bertolero, A. (1995) Theoretical flight ranges of waders resting in the Ebro Delta ... Dunn, PO, May, TA & McCollough, MA (1988) Length of stay and fat content of ...
Animal Conservation, Jul 3, 2009
The presence of the Mediterranean pond turtle Mauremys leprosa in the Ebre Delta (Catalonia, nort... more The presence of the Mediterranean pond turtle Mauremys leprosa in the Ebre Delta (Catalonia, northeast Spain) is well documented after the late 1970s, when the first reptile distribution lists were published. Owing to the fact that the species was considered scarce, a reintroduction programme based on the release of individuals at sites with potential habitat suitability was launched. From 1999 to 2001, 234 turtles of different ages were released and subsequently monitored until 2007, in order to make a conservation diagnosis using five assessment criteria. These criteria were body condition, individual growth, reproduction, survival and population growth rate. Despite the relatively large number of turtles released, no viable population resulted from the programme. Assessment criteria suggested that: (1) released individuals showed good physical condition and satisfactory growth (the only positive results); (2) reproduction was almost absent; (3) local survival was reduced compared with that of Spanish wild populations of the species; (4) temporary emigration was high; (5) the growth rate of the population was negative. In conclusion, the results suggested that the habitat at the Ebre Delta marshes may not be favourable to the species, and that the scarce historical data record may indicate a relatively low-quality habitat; the few records may correspond to individuals dispersing from the river, a more suitable habitat. Thus, we conclude that historically scarce records may be the result of natural patchiness and heterogeneous distributions, and they are not necessarily a good indicator of relict, decimated populations. Good assessment criteria, as those proposed and used here, are necessary tools to assess results in reintroduction projects to recover endangered chelonian populations.
Animal Conservation, Aug 1, 2007
Although reintroduction programmes are often implemented for recovering animal populations, proje... more Although reintroduction programmes are often implemented for recovering animal populations, projects seldom monitor the long-term survival of released animals. In addition, although many releases may occur in the same area, little is known about how the survival of successive release batches is affected by the presence of conspecifics and density dependence. Here, we use multi-state capture-recapture modelling (combining information from recaptures and recoveries) to analyse the survival of two batches of Hermann's tortoise Testudo hermanni hermanni released in a 10-year interval and monitored for 18 years at the Ebro Delta (western Mediterranean). We also tested whether the released animals experienced lower survival (i.e. a release cost) before becoming familiar with the new environment. Although we used a hard-release method, neither group experienced a short-term release cost. Annual survival of both groups differed and was not negatively affected by density-dependent factors. Annual survivorship of the first group of released tortoises was constant and very high (0.945, SE = 0.011), and similar to that estimated from several natural populations. The presence of a terrestrial predator in 1 year (before the release of the second group) significantly decreased the survival of tortoises (0.819, SE = 0.073). Strikingly, survival of the second batch was significantly lower than that of the first group after the first years of release (0.775, SE = 0.049). Although survivorship for the first group suggested that habitat quality was high, the second group seemed not to acclimate well to the new environment, possibly due to the presence of resident tortoises. From a management perspective, reintroduction programmes of the Hermann's tortoise are a successful strategy for its recovery. Nevertheless, it seems advisable to avoid: (1) the release of tortoises at the core of well-established populations and (2) areas with a high density of predators, which can jeopardize the reintroduction success, especially when the number of released individuals is small.
Scientific Reports, Oct 30, 2020
Social interactions, through influence on behavioural processes, can play an important role in po... more Social interactions, through influence on behavioural processes, can play an important role in populations' resilience (i.e. ability to cope with perturbations). However little is known about the effects of perturbations on the strength of social cohesion in wild populations. Long-term associations between individuals may reflect the existence of social cohesion for seizing the evolutionary advantages of social living. We explore the existence of social cohesion and its dynamics under perturbations by analysing long-term social associations, in a colonial seabird, the Audouin's gull Larus audouinii, living in a site experiencing a shift to a perturbed regime. Our goals were namely (1) to uncover the occurrence of long-term social ties (i.e. associations) between individuals and (2) to examine whether the perturbation regime affected this form of social cohesion. We analysed a dataset of more than 3500 individuals from 25 years of monitoring by means of contingency tables and within the Social Network Analysis framework. We showed that associations between individuals are not only due to philopatry or random gregariousness but that there are social ties between individuals over the years. Furthermore, social cohesion decreased under the perturbation regime. We sustain that perturbations may lead not only to changes in individuals' behaviour and fitness but also to a change in populations' social cohesion. The consequences of decreasing social cohesion are still not well understood, but they can be critical for the population dynamics of social species.
Biological Conservation, 2018
Translocations to restore populations of endangered species are an important conservation tool, b... more Translocations to restore populations of endangered species are an important conservation tool, but a reliable diagnosis is needed to assess their success. We used capture-recapture modeling to analyze the adult apparent survival of released and resident tortoises in two translocation projects in Spain monitored for 14 and 29 years. We tested if long-term survival rates differ between released and resident individuals, if survival was lower during the phase of establishment (i.e. release cost), how long acclimation lasts and if increased density due to releases affects survival. We found lower survival of released tortoises during the phase of establishment (1 to 3 years) when residents were already present. After establishment, survival was very high and unaffected by density-dependence. Body condition before release was similar between recaptured and dead/missing tortoises, and did not predict establishment survival. Stochastic population viability analysis showed that success when releasing small numbers of individuals strongly depends upon adult long-term survival. Release of small second batches of tortoises was not sensitive to a growing population, regardless of its release timing. Our results highlight long-term survival as crucial in translocation projects of long-lived species, invalidating short-term (first year) survival assessment, when survival release cost does not match long-term survival. A release cost of different duration should be included in model estimation before modeling predictions. Releasing tortoises (for welfare of captive individuals or for mitigating human negative impacts) in an already established population is not recommended under most circumstances. Acclimation cost is followed by survival approaching wild counterparts. If this milestone is not achieved, the project needs to be carefully assessed to adopt other management options or should be stopped altogether.
Trabajo presentado en la 2nd World Seabird Conference, celebrada en Ciudad del Cabo, Sudafrica, d... more Trabajo presentado en la 2nd World Seabird Conference, celebrada en Ciudad del Cabo, Sudafrica, del 26 al 30 de octubre de 2015
Trabajo presentado en el Ecology and Behaviour, celebrado en Toulouse (Francia), del 18 al 21 de ... more Trabajo presentado en el Ecology and Behaviour, celebrado en Toulouse (Francia), del 18 al 21 de mayo de 2015
Revista catalana d'ornitologia = Catalan journal of ornithology, 2005
We studied the foraging habitats of the Little Tern Sterna albifrons while breeding at the Ebro D... more We studied the foraging habitats of the Little Tern Sterna albifrons while breeding at the Ebro Delta (NE Spain). Most (95%) of the foraging terns were observed less than 4 km away from the nearest colony. Little terns preferred channels and lagoons for foraging; lagoon mouths were used in proportion to their availability, and saltmarshes were avoided. In spite of the large surface area of rice paddies sampled, this habitat was seldom used. We found that the frequency of birds observed foraging at freshwater and brackish habitats did not differ significantly from the frequencies to be expected based on the availability of these habitats. Very few birds were observed foraging in marine habitats. The presence of suitable foraging grounds within a radius of 4 km may also influence the Little Tern's selection of breeding habitat.
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Papers by Albert Bertolero