Juan Bécares

• biologist
• Researcher at Cory's - Investigación y Conservación de la Biodiversidad

Knowledge of the spatial distribution and population trends of threatened species is essential to improve their conservation status. We analysed a 21-year dataset (2000− 2020) with at-sea counts of the critically endangered Balearic shearwater (Puffinus mauretanicus) to understand its distribution, habitat suitability, population trends, overlap wi...

Accidental capture in fishing operations (bycatch) is one of the main threats affecting seabirds worldwide. Available data on this issue remains limited and is often insufficient to evaluate the extent and characteristics of bycatch. The costs of placing independent observers on vessels, or gather verifiable and independent data via electronic syst...

Animals explore and prospect space searching for resources and individuals may disperse, targeting suitable patches to increase fitness. Nevertheless, dispersal is costly because it implies leaving the patch where the individual has gathered information and reduced uncertainty. In social species, information gathered during the prospection process...

1. Spatial modelling is an important research tool to improve our knowledge about the distribution of wildlife in the ocean. Using different modelling techniques (MaxEnt and a generalized linear mixed model), a predictive habitat suitability model was developed for one of the most threatened seabirds in the world: the Balearic shearwater, Puffinus...

Human fisheries provide scavengers with abundant and predictable feeding opportunities that may schedule their behavioural patterns. Using miniaturized global positioning system (GPS) tracking technology, we evaluated how Audouin’s gull (Ichthyaetus audouinii), a Mediterranean endemic seabird that makes extensive use of feeding opportunities provid...

This document, the MRR, includes the description of the criteria and species assessed, along with compilation of the results obtained during the implementation of the pilot monitoring programmes under the MSFD for marine birds, mammals and turtles in the three Macaronesian archipelagos (Azores, Madeira and Canary Islands) but also from other additi...

We studied the post-fledging movement of two sibling (male and female) juvenile Barbary Falcons (Falco peregrinus pelegrinoides) hatched in Lanzarote (Canary Islands) in 2011 using satellite tracking. Birds were tracked from fledging in May to the end of November, when the signals of both transmitters were lost. During the first 45 d following fled...

Marine megafauna, including seabirds, are critically affected by fisheries bycatch. However, bycatch risk may differ on temporal and spatial scales due to the uneven distribution and effort of fleets operating different fishing gear, and to focal species distribution and foraging behavior. Scopoli's shearwater Calonectris diomedea is a long-lived s...

Fisheries provide an abundant and predictable food source for many pelagic seabirds through discards, but also pose a major threat to them through bycatch, threatening their populations worldwide. The reform of the European Common Fisheries Policy (CFP), which intends to ban discards through the landing obligation of all catches, may force seabirds...

http://www.seo.org/boletin/seguimiento/migracion/01_gaviota_audouin/

Systematic data collection of cetacean and seabird distribution in offshore waters is challenging due to the high costs of performing oceanic surveys. Opportunistic platforms such as ferries have proven to be effective in gathering consistent data in local areas and in large offshore routes. Data are used to study the spatial and temporal distribut...

Systematic data collection of cetacean and seabird distribution in offshore waters is challenging due to the high costs of performing oceanic surveys. Opportunistic platforms such as ferries have proven to be effective in gathering consistent data in local areas and in large offshore routes. Data are used to study the spatial and temporal distribut...

Systematic data collection of cetacean and seabird distribution in offshore waters is challenging due to the high costs of performing oceanic surveys. Opportunistic platforms such as ferries have proven to be effective in gathering consistent data in local areas and in large offshore routes. Data are used to study the spatial and temporal distribut...

Systematic data collection of cetacean and seabird distribution in offshore waters is challenging due to the high costs of performing oceanic surveys. Opportunistic platforms such as ferries have proven to be effective in gathering consistent data in local areas and in large offshore routes. Data are used to study the spatial and temporal distribut...

Systematic data collection of cetacean and seabird distribution in offshore waters is challenging due to the high costs of performing oceanic surveys. Opportunistic platforms such as ferries have proven to be effective in gathering consistent data in local areas and in large offshore routes. Data are used to study the spatial and temporal distribut...

Fisheries and seabirds are intimately associated as both exploit the same productive areas. Some seabirds take advantage of fishery discards, mostly generated by trawlers, as a supplementary foraging resource, changing their foraging strategies linked to this predictable food. Thus it is expected that any change in fishing practices will have impor...

In, SEO/BirdLife 2012. Atlas de las aves en invierno en España 2007-2010. Ministerio de Agricultura, Alimentación y Medio Ambiente-SEO/BirdLife. Madrid.

Figure S1. (A) Parameter estimate ± standard error for the logistic GLMM to fit the proportion of rice field positions over the total feeding positions. Weekends were used as a reference level in the analysis. (B) 95% CI of the estimated proportion of rice field positions derived from the model. Figure S2. (A) Parameter estimate ± standard error fo...

Although the breeding ecology of Audouin’s gull has been widely studied, its spatial distribution patterns have received little attention. We assessed the foraging movements of 36 GPS-tracked adult Audouin’s gulls breeding at the Ebro Delta (NW Mediterranean), coinciding with the incubation period (May 2011). This also coincided with a trawling mor...

Some seabird species have learnt to efficiently exploit fishing discards from trawling activities. However, a discard ban has been proposed as necessary in Europe to ensure the sustainability of the seas. It is of crucial importance for the management and conservation purposes to study the potential consequences of a discard ban on the foraging eco...

CapsuleThe breeding foraging and post-breeding dispersal movements of five satellite-tagged Bulwer's Petrels from the Canary Islands were recorded. Foraging trips lasted 5.6 days in average (n=3), while the mean distance covered was 1261 km, and foraging areas were located over the continental slope and the adjacent pelagic waters, around 1200-2000...

Aim Apical pelagic species forage in predictable habitats, and their movements should signal biologically and ecologically significant areas of the marine ecosystem. Several countries are now engaged in identifying these areas based on animal tracking, but this is often limited to a few individuals from one breeding population, which may result in...

El trabajo “Huella pesquera en las 39 ZEPA marinas de España” se enmarca en el proyecto LIFE+ INDEMARES y tiene por objetivo evaluar el impacto de la pesca sobre las aves marinas por las que estos espacios han sido declarados. Para el estudio se han utilizado diversas fuentes de información, con datos correspondientes al periodo 2008-2012. Para la...

Protected areas play a key role in the preservation of biodiversity, but their implementation at sea is lagged behind terrestrial environments, especially in offshore areas. Here we describe the identification of foraging hotspots off the Mediterranean Iberian coast using three Procellariiform species as examples, and assess the stability of these...

The Balearic Shearwater Puffinus mauretanicus is considered the most threatened seabird in Europe, based on a prediction of extinction within 3 generations in average. Such prediction was computed in 2004, based on a population estimate of 2,000 breeding pairs at that time. However, the breeding population has been recently updated to 3,193 pairs....

La pardela mediterránea cría en islotes e islas en buena parte de la cuenca mediterránea, principalmente en la parte central y oriental, y de manera aislada en el mar Negro (Bourgeois y Vidal, 2008). Entre agosto y febrero hace movimientos dispersivos restringidos también a estas dos cuencas marinas. Las colonias más cercanas a las costas españolas...

El grueso de la población mundial reproductora cría en España, con cerca de 20.000 parejas en el año 2007 (Genovart et al., 2008), pero una parte muy importante de ésta pasa el invierno en las costas norteafricanas atlánticas (De Juana et al., 1987), incluyendo la gran mayoría de las aves jóvenes e in-maduras (Oro y Martínez Vilalta, 1994). En la E...

La pardela balear se reproduce exclusivamente en las islas Baleares, iniciando las puestas a finales de febrero o principios de marzo (Ruiz y Martí, 2004). Tras la reproducción abandona el Mediterráneo y ocupa las aguas atlánticas del suroeste de Europa (Le Mao y Yésou, 1993; Mouriño et al., 2003), pero el grueso de la población se encuentra ya de...

Se trata de una especie marina pero de hábitos poco pelágicos, en muchas ocasiones ligada a bahías, rías o desembocaduras, de manera que ni los cen-sos desde cabo ni los censos de aves acuáticas invernantes (focalizados en zonas húmedas dulceacuícolas) cubren el total de la población invernante. Su muestreo es, por tanto, muy complicado con la meto...

Marine censuses of the four species of small procellariforms that breed in the Canary Islands formed part of the fieldwork within the framework of the Project Life Important Areas for Seabirds (IBAs) in Spain and which was carried out by SEO/BirdLife. In total, more than 180 hours of census work was carried out in Canary Islands waters, both aboard...

The results of the censuses of the European Storm-petrel Hydrobates pelagicus carried out within the project Life Important areas for seabirds (IBA) in Spain and carried out by SEO/BirdLife have enabled knowing the distribution and abundance of this species in Spanish peninsular waters after more than 900 hours of censusing. The species shows a pre...

The observations of Madeiran Storm-petrel Oceanodroma castro in waters of northwestern Spain (Galician Bank) during July and, especially, in September are, with the exception of the four accepted records by the Spanish Rarities Committee (CR/SEO), the first in Spanish Peninsular waters. These observations were the result of pelagic embarcations off...

The Balearic Shearwater is regular off the Catalan coast throughout most of the year apart from the post-breeding dispersal period (summer). It is commoner in the southern and central sectors, which are closer to its breeding grounds. In winter it may form thousand-strong flocks, which vary in size from one year to another, probably due to changes...

The Velvet Scoter is only present in winter in Catalonia and in very small numbers, and its abundance depends on both the severity of the winter in northern Europe and its breeding success. In Catalonia it occurs mainly in the bay of Roses and in the waters off the Llobregat and Ebro deltas. It usually appears in groups of fewer than 5 individuals...

The regular western limit of the distribution of the Yelkouan Shearwater lies off the Catalan coast, where it is common most of the year. It shows a clear preference for the colder waters of the northern part of the coast, which are closer to its breeding grounds. In winter this shearwater tends to congregate in coastal waters that are particularly...

The Common Scoter is an almost exclusively marine species in winter. During the breeding season it is commonest in Russia and most birds winter in the Baltic Sea, although a few thousands are found each winter off the coasts of the British Isles and the Atlantic coast of the Iberian Peninsula and Morocco. During the Atles period, this scoter was de...

Distribution and identification of the best areas for Pin-tailed Sandgrouse Pterocles alchata during the breeding season in Catalonia Using standardized and non-standardized surveys, we obtained evidence of reproduction that allowed us to produce a distribution map of the Pin-tailed Sandgrouse at 1x1 km resolution for Catalonia. The standardized ob...

Trophic segregation has been proposed as a major mechanism explaining the coexistence of closely related animal taxa. However, how such segregation varies throughout the annual cycle is poorly understood. Here, we examined the feeding ecology of the two subspecies of Cory's shearwater, Calonectris diomedea diomedea and Calonectris diomedea borealis...

An understanding of the distribution and habitat associations of far-ranging marine predators is being increasingly applied to protect these species from anthropogenic threats at sea (e.g. oil spills and fisheries bycatch). Within this framework, this research on Cory's shearwater Calonectris diomedea integrates vessel-based survey and tracking dat...