Black Vulture Colony Tracking

buitre negro posadoThe black vulture (Aegypius monachus) is one of the most threaten birds in Europe. That situation is clearly stated in the Ordinance 79/409/CEE related to the wild birds’ preservation, including that specie in its Annex I summoning the SPA (Birds Special Protection Zone) declaration to every area counting with at least a nesting pair. The black vulture populations of the Sierra de Guadarrama are distributed in two SPAs within the National Park, with populations in Rascafría, Valsaín, River Moros, River Pirón and Navafría. If we consider the Sierra de Guadarrama black vulture several populations as a single one, it will be the fourth largest colony in Spain after the following ones: Sierra de San Pedro, Monfragüe (in Extremadura) and Cabañeros (in Castilla La Mancha).

Those populations have a great interest for the black vulture preservation in the center of the Iberian Peninsula, because they suppose nearly 4% of the Spanish population. Additionally, that colony is located at a short distance of a large city as Madrid, in a highly touristic and recreational area, and also within forests still having logging activities.

The complex situation of the specie implies the need of its populations detailed information availability, to improve its monitoring, and to reconcile the zone existing exploitations with the preservation of that threaten specie populations. In addition, those data have to be gathered during large yearly periods due to the specie long biological cycle; allowing this way to establish significant relations between different factors and the colony and its evolution, justifying then the management proposals. In any case, the knowledge of the nest location of every pair in each season, and its reproductive phenology, is imperative for the correct monitoring of that specie population in relation with the forest exploitation and logging works made usually in the woods where the colony is located.

With the objective of maintaining an adequate level of knowledge for the National Park populations’ preservation, we undertook in 1992 the location of the black vulture platforms placements in the Alto Lozoya SPA, one of the most northern of the Iberian Peninsula. For that task, we count since 1997 with the Ornithology Spanish Society (SEO/Birdlife) cooperation, contributing since that year to nowadays, to a thorough and detailed tracking of the colony.

The main objective of the tracking is the reproductive population condition updating, emphasizing specially the number of pairs, the egg-laying periods, the chicks’ hatches, the first flight dates and the young specimen emancipation.

The colony evolution

The first known estimations of the black vulture colony at the zone are from 1973, quantifying the population in the Madrilenian slope in 6 pairs. The last 2015 data release a total number of 113 pairs (102 breeding and 11non-breeding) for the Madrilenian section of the National Park. A 58,4% of those pairs are located in private ownership mounts and the rest in public ownership ones. Among the 102 pairs with eggs-laying in 2015, 36 failed (35,3%). The remaining breeding pairs succeeded in their reproduction, with 66 flying chicks in the colony. During the tracking tasks have been located 141 black vulture platforms, of which 117 are hold in good condition.

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The population trend is clearly positive, with a 291% growth between 1997 and 2015. The average productivity figures (flying chicks per pair) and breeding success (flying chicks per breeding pair) in 2015 are 0,58 and 0,65 respectively. The number of flying chicks has been high and above the average rate of the last five seasons.

Marking

A relevant part of the preservation tasks undertaken in the last decade, has been devoted to part of the black vulture population marking. The chicks banding in the Alto Lozoya SPA colony started in 1998; since then 742 chicks have been banded, of which 66 have been made during the 2015 summer, supplying much information about mortality causes and spots, dispersion areas, philopatry, etc. During the banding process, we register the basic biometrics of all the birds, and biologic samples for their sexing and sanitary analysis. Among the 2015 birds controls in remote areas of the colony and outlying the routine feeding areas, we should highlight a vulture banded in 2014 and controlled later on in the Boumort Hunting National Reserve, in Lérida.

The adults banding started in 2003, and 22 adult specimens have been already marked with emitters. Those tasks are facilitating the compiling of a large amount of information on the black vulture of that colony, which allows to better understand its biology, the problems they may face and therefore to establish solutions to preserve that threaten specie.

In 2014, we marked a chick with a GPS emitter, knowing that way with a great detail its daily activity. Those emitters, unlike the ground emitters, do not need a costly personnel team in situ, to track the specimen on a daily basis. The localizations are downloaded via internet, and with cartography elements and aerial photography, its feeding areas and home ranges can be studied, being necessary to go in situ only on a punctual basis to obtain additional specific information of the areas used by the specimen.

Nowadays there are two specimens marked with satellite-GPS emitters.