Article

Survival of a small reintroduced griffon vulture population in the Apennines: Insights from Global Positioning System tracking

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  • Pollino National Park, Italy
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Abstract

Conservation translocations ( e. g., restocking, reintroductions) represent efficient tools to prevent the extinction or favouring the return of previously extirpated populations into the wild. Evaluating demographic parameters of translocated populations is a key issue to assess and monitor their conservation status and to provide evidences useful to implement management actions aimed at long-term conservation results. We report first data on survival estimates and related mortality causes for a reintroduced population of Eurasian griffon vultures ( Gyps fulvus) in the central-southern Apennine, Italy, from satellite telemetry data. Twenty vultures have been fitted with solar-powered Global Positioning System (GPS) tags in Pollino National Park (PNP, southern Italy, N = 9) and Monte Velino Reserve (MVR, central Italy, N = 11). Survival has been estimated on a total amount of 173,568 GPS fixes from December 2016 to October 2020 (1415 days) using the Fleming-Harrington estimator. Five, out of 20 vultures, died by poisoning (40%), collision with wind turbines (20%) and of unknown causes (40%). Two birds dispersed from MVR to France (though they later came back) and one from PNP to Croatia. Estimated survival rate across the whole study period was 0.709 (±0.11, SE; 0.523–0.961, 95% CI), and annual survival rate was 0.915 (±0.06, SE; 0.846–0.990, 95% CI). No significant differences in survival rates have been detected according to sex or age. As mortality in our study was mainly human-caused, we urge relevant institutions and agencies to strengthen and effectively establish anti-poison strategies, as well as implementing mitigation and prevention measures for the existing and planned wind farms. The establishment of a long-term viable population in the central-southern Apennines will depend upon both lower levels of human-caused mortality and habitat preservation.

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BIOGEOGRAPH/A — vol. X VII — 1993 (Pubb//‘Cato /7 31 otmbre 1994) ll popolamento animale e vegetale delI'Appennino Urnbro-Marchigiano Una avifauna dell’Appennino centrale nel ’500: il trattatello «Cognitione degl’uccelli et animali pertinenti al’aeregg e le lettere di Costanzo Felici da Piobbico ad Ulisse Aldrovancli MAS SIMO PANDOLFI (qq) & GIANNA ZANAZZO (qq“qq) (q‘) Irtzfuto dz' Sczienze Motfologic/9e - Unzberrzhi dz' Urkino - (q“q‘) Via G. Barri, 6 — Padowz. Key words: Historical fauna, XVI Century, Central Apennines, Birds. SUMMARY Original descriptions of 108 species of wild birds are reported from letters and a tractatus sent by Co- stanzo Felici, a 16th century Marchean doctor, to the Bologna natural historian Ulisse Aldrovandi. The letters were written during the period 1563-1573 at the specific request of Aldrovandi who \Vished to know the situation of the local avifauna. The mass of information refers above all to the mountains of the Pesaro hinterland and supplies a surprising amount of data both on this area of the Apennines and on the whole avifauna population of Italy. What are completely original are the data on nesting for a certain number of species now extinct in the Central Apennines, or indeed throughout Italy: Larnmergeier Gypaetuiq earbatur, Black Vulture Aegypi/ts momzc/Jztr, Griffon Vulture Gypr fizlvzzs, White Pelican Peleczmur anocrotalzzr, Raven Corvus carax and Rock Dove Colzmzbzz lz'w'a. A comparison of the situation whith that reported in Felici’s list shows that at least 15 species have become extinct in the Pesaro Apennine area and another 15 are certainly less common than they Vere in the 16th century. PREME S SA Tra i nurnerosi corrispondenti cli Ulisse Aldrovandi, il medico marchigiano Costanzo Felici(1) fu uno dei piu assidui ed ascoltati(2). La loro arnicizia, nata (1) Costanzo Felici nacque nel secondo decennio del ’500 a Casteldurante (l’attuale Urbania). Egli pero preferiva definirsi originario di Piobbico, nell’alto Pesarese, dove si erano trasferiti i suoi avi che avevano do- vuto abbandonare Lucca verso il 1330 in seguito alle discordie sorte tra Guelfi e Ghibellini. La sua famiglia annovero tra i propri rnembri letterati, rnatematici, giureconsulti, rnilitari e prelati. Felici studio at Perugia e a Padova clove il 31 agosto del 1552, consegui la laurea in arte e medicina, che gli consenti di esercitare la pro~ fessione di medico a Piobbico, a Sant’Angelo in Vado, a Pesaro, a e a Urbania. Al tempo stesso coltivo con notevoli risultati gli studi naturalistici e storici. Oltre che con Ulisse Aldrovandi, ebbe contatti con altri il- lustri scienziati, tra i quali Girolamo Cardano, l’Anguillara, Rigacci, Moderato ed altri. Mori a Pesaro il 5 feb- hraio 1585. (2) Che Felici fosse uno dei piu assidui e ascoltati collaboratori di Aldrovandi lo si deduce prendendo in esame le sue lettere e gli appunti che da queste traeva il destinatario (cf. il ms 136 della Biblioteca Universitaria di Bologna. Fondo Aldrovandi. t. H. c. 260v—263v).
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Little is known of the life history of vultures. The reintroduction program of Griffon Vultures (Gyps fulvus fulvus) in the Causses (south of the Massif Central, France) and extensive monitoring by capture-mark-resighting of the released birds allowed us to obtain the first estimates of their survival. Adult survival rates are high (x̄ = 0.987 ± SE of 0.006). A release effect on adult survival was detected (only 0.743 ± 0.006 survival during the first year after release). Young born in the wild (less than three years old) had an annual survival rate of 0.858 ± 0.039. Mortality causes and erratic behavior of immature birds are considered in order to assess the effectiveness of this reintroduction program. Our results indicate that reintroductions of vultures and similar species should use adults that have bred in captivity within the target area rather than juveniles or immatures.
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The estimation of survival distributions for animals which are radio-tagged is an important current problem for animal ecologists. Allowance must be made for censoring due to radio failure, radio loss, emigration from the study area and animals surviving p88l. :~the end of the study period. First we show that the Kaplan-Meier .procedure wid~ly used in medical and engineering studies can be applied to this problem. An example using some quail data is given for illustration. As radios maItunction -or are lost, new radio-tagged animals have to be added to the study. We show how this modification can easily be incorpor~.ted inf.<? the basic Kaplan-Meier procedure. Another example using quail data is used to illustrate the extension. We also show how the log rank test commonly used to compare two survival distributions can be generalized to allow for additions. Simple computer programs which can be run on a PC are available from the authors.
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Two nonparametric estimators o f the survival distributionare discussed. The estimators were proposed by Kaplan and Meier (1958) and Breslow (1972) and are applicable when dealing with censored data. It is known that they are asymptotically unbiased and uniformly strongly consistent, and when properly normalized that they converge weakly to the same Gaussian process. In this paper, the properties of the estimators are carefully inspected in small or moderate samples. The Breslow estimator, a shrinkage version of the Kaplan-Meier, nearly always has the smaller mean square error (MSE) whenever the truesurvival probabilityis at least 0.20, but has considerably larger MSE than the Kaplan-Meier estimator when the survivalprobability is near zero.
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Intraspecific competitive behaviours were studied in a reintroduced population of Griffon Vultures Gyps fulvus in order to describe the pattern of competition between ages and sexes, assess the effect of reintroduction on competitive behaviour, and study the potential consequences of food management on competition. There was no evidence for a difference in feeding or display rates between age classes. However interaction rates, aggressiveness and dominance were higher in old adults than in the other age classes. No difference in the pattern of competition was found between sexes. There was no difference in the competitive ability (feeding rate and dominance) of reintroduced and wild-bred individuals. Feeding rates increased with resource availability. Group size also increased with food mass, but was lower than the theoretical maximum number of birds. This may be evidence of competition by interference where some individuals are able to increase their feeding rate by the exclusion of others. An increase in both the number of carcasses and the number of feeding sites is thus recommended to induce dispersal and reduce this competition.