1. INFLUENCE OF RADIOTRACKING NECKLACES ON THE SURVIVAL OF RED-LEGGED PARTRIDGE (Alectoris rufa) PÉREZ, J.A.; DÍEZ, C.; BARTOLOMÉ, D.; ALONSO, M.E.; GAUDIOSO, V. Dpto. Producción Animal II, Facultad de Veterinaria de León. 24071. España. E.mail: dp2jpg@unileon.es III INTERNATIONAL SYMPOSIUM ON WILD FAUNA (ISCHIA, ITALY)dp2jpg@unileon.es INTRODUCTION. In experimental repopulations is neccesary equip the animals with radiotracking equipments to control the survival, causes of mortality, and adaptationand integration in the wild. More used equipments in galliphorms are radio transmitter necklaces, with a weight of 9.8 g., less than 5 % of body weight (CARVALHO, 1998). However, they present a fine wire as antenna over partridges back that could appear to be as a visual sign to a potential aerial predator (PÉREZ, 1999). OBJETIVES. A protocol to evaluate the influence of radiotracking necklaces over experimental partridges was carried out in two consecutive years, with two study periods each year. MATERIAL AND METHODS. ANIMALS: Thirty two adult red-legged partridges coming from a commercial game farm. We released 16 partridges each year, in two periods, spring and autum (8+8). Numbered metallic rings were placed to all partridges, and half of them were equipped with Biotrack  radio transmitter necklaces, with a weight of 9.8 grams and minimum autonomy of 11 months (Photo 1). RELEASE METHOD: The partridges were distributed paired along four 0.5 has. control enclosures built with cynegetic fence (2 m high) to avoid terrestrial predation. This enclosures had vegetation characteristic of the environment, a drinking trough of constant level and dispersed seeds of cereals on the floor. All the animals were subjected to a manipulation of the wings feathers to avoid them flying. We proceeded to cut down the middle primary and secundary remiges of the rigth wing (Photo 2). PARTRIDGES LOCALIZATION: Once released it was carried out individual daily birds localizations, five days per week during the first two weeks and two days per week from this moment, through localization trips and using the radio-tracking system, a receiving Yaesu  with directional antenna (GORTÁZAR et al., 1997). Only in one case we must use a hunting dog (pointer). CAUSES OF PARTRIDGES DEATH: When a partridge was found dead, it was take a photogragh and it was determined the cause, framing it in one of the following groups: -Air predation, fleshed bones and feathers started up cleanly from the quill (Photos 3 and 4). -Other cause of death, like starvation, illness, accident... When possible the cadaver was picked up and a formal autopsy was carried out to check the body condition, plumage state, presence of food in the crop and gizzard, symptoms of common pathologies, etc. DATA ANALYISIS: To carry out the statistical study the computer program statistical SPSs© (version 10.0) for WINDOWS© was used. RESULTS. SURVIVAL: The obtained results reveal a disproportionate pressure of predation in the two years, as in spring as in autum, and a great difficulty for the manipulated partridges to overcoming the successive attacks from aerial predators. In this way, just four animals survived more than one week, and only two more than two weeks. There were no statistical significant differences between survival results to the two experimental periods, spring and autum (Graphic 1), as not between differencial survival results to males and females so both parameters will be analized as a whole. We don’t found too statistical significant differences between survival results obtained from partridges equiped with necklaces and partridges without radiotracking equipment (Graphics 2, 3, 4 and 5). The mean survival rate was of 6.0625 days, 6.8125 to radiomarked partridges and 5.3125 to non-radiomarked. CAUSES OF DEATH : Of the total of registered drops, we assigned 93.75% to air predation, and 6.25% (two cases) to other causes of death, both of them dued to accident with the cynegetic fence. There were no statistical differences between two years. BIBLIOGRAPHY. CARVALHO, J.; CASTRO PEREIRA, D.; CAPELO, M.; BORRALHO, R. (1998). Red-legged partridge (Alectoris rufa) restocking programs: their success and implications on the breeding population. Gibier Faune Sauvage, Game Wildlife vol. 15: 465-474. GORTÁZAR, C.; MARCO, J.; FERNÁNDEZ DE LUCO, D. (1997). Repoblaciones con perdiz roja. Su efectividad en la práctica. Trofeo 326: 24-31. PÉREZ, J.A. (1999). Utilización del radioseguimiento para la valoración del comportamiento de los animales empleados en repoblaciones de perdiz roja (Alectoris rufa). Tesina. Univ. de León. 131 pp. Graphic 1: Mean survival rate for the study periods. Graphic 2: Survival evolution of released partridges in first year spring. Graphic 4: Survival evolution of released partridges in second year spring. Graphic 3: Survival evolution of released partridges in first year autum. Graphic 5: Survival evolution of released partridges in second year autum. Photo 1: Numbered rings and radiotracking necklaces. Photo 2: Rigth wings manipulation. Photo 3: Body dead from an air predated partridge. Photo 4: Subadult goshawk predating over an experimental partridge. DISCUSSION. Within the experimental context proposed, it does not appear that the necklaces influence the survival of the partridges in a significant way, principally because of the great difficulty for the manipulated partridges to overcoming the successive attacks from aerial predators. Moreover, the animal which more time remained in the control enclosures was a radiomarked partridge, which survived 67 days, followed by a non-radiomarked one which urvived 18 days.