27 research outputs found
Influence of Snowmelt Timing on the Diet Quality of Pyrenean Rock Ptarmigan (Lagopus muta pyrenaica): Implications for Reproductive Success
The Pyrenean rock ptarmigan (Lagopus muta pyrenaica) is the southernmost subspecies of the species in Europe and is considered threatened as a consequence of changes in landscape, human pressure, climate change, and low genetic diversity. Previous studies have shown a relationship between the date of snowmelt and reproductive success in the Pyrenean ptarmigan. It is well established that birds laying early in the breeding season have higher reproductive success, but the specific mechanism for this relationship is debated.
We present an explicative model of the relationship between snowmelt date and breeding success mediated by food quality for grouse in alpine environments. From microhistological analyses of 121 faecal samples collected during three years in the Canigou Massif (Eastern Pyrenees), and the assessment of the chemical composition of the main dietary components, we estimated the potential quality of individual diets. Potential dietary quality was correlated
with free-urate faecal N, a proxy of the digestible protein content ingested by
ptarmigan, and both were correlated with phenological stage of consumed plants, which in turn depends on snowmelt date. Our findings suggest that the average snowmelt date is subject to a strong interannual variability influencing laying date. In years of early snowmelt, hens benefit from a longer period of high quality food resources potentially leading to a higher breeding success. On the contrary, in years of late snowmelt, hens begin their breeding period in poorer nutrient condition because the peaks of protein content of their main
food items are delayed with respect to laying date, hence reducing breeding performance. We discuss the possible mismatch between breeding and snowmelt timing
Studies in Willow Grouse Lagopus lagopus of some possible measures of condition in birds
A field evaluation of the Finnish 3-man chain: a method for estimating forest grouse numbers and habitat use
The Finnish 3-man chain, a strip transect method for estimating grouse numbers, was tested using radio-tagged birds, 20Capercaillie and39 Black Grouse, in 104 field trials . The proportion counted by the census chain was 54-58% for adult Capercaillie without young and 61-64% for Black Grouse . Only one Black Grouse brood of 11 was not recorded by the chain. Most uncounted Capercaillie ran aside from the strip, while most uncounted Black Grouse remained crouching on the strip. Overall about 80% of the combined number of adults and juveniles should be detected in an average production year with this transect method. The density of covering vegetation influenced the tendency of Black Grouse to remain on the strip. Nevertheless, since almost all of the observed birds moved only short distances, habitat estimates at sites where birds flew up appeared to be a good estimate of the habitat of undisturbed birds
Wildlife monitoring in Finland: online information for game administration, hunters, and the wider public
Die Wirksamkeit einer Methode zur Kontrolle der parasitÀrenr Helminthenbelastung von Fasanen (Phasianus colchicus) im Freiland
Forest structure as a determinant of grouse brood occurrence â An analysis linking LiDAR data with presence/absence field data
Individual and Environmental Determinants of Daily Black Grouse Nest Survival Rates at Variable Predator Densities
SuccÚs de lùchers traditionnels de perdrix rouges en vue d'assurer le repeuplement en petit gibier dans des territoires situés en Aragon (Nord-Est de l'Espagne) et présentant une faible densité de population
[EN] Release of pen-reared red-legged partridges(Alectoris rufa) is a common game management tool in Spain. In spite of three million partridges raised yearly in captivity, at present time, effectiveness of traditional restocking has received little research. Consequently, we investigated the survival of 62 radio-tagged partridges under two different release conditions: scattered and grouped, imitating for our purposes the procedure employed by Spanish hunters and gamekeepers. The null-hypothesis of no difference between the survival probabilities observed in the grouped versus disperse releases was rejected (p = 0.019). In both experiences, 25 to 34 % of the mortality took place in the first 72 hours after release. Thereafter, the average survival of the disperse-released partridges was clearly higher than those of the grouped ones, with 37.4 ± 1.8 % of the former surviving the first month in comparison to only 5.8 ± 1.1 % of the latter (figure). Red fox(Vulpes vulpes) and golden eagle(Aquila chrysaĂ«tos) were suspected predators in 37 of 39 kills (95 %). Traditional restocking of red-legged partridges in Spain is not an effective management tool to enhance wild populations. In any case, the technique may be improved by scattering the release sites.[DE] Die Auswilderung von gezĂŒchteten RothĂŒhnern(Alectoris rufa) ist in spanischen Jagdrevieren ĂŒblich. Obwohl jĂ€hrlich etwa drei Millionen RothĂŒhner in Flugvolieren produziert werden, wurde der Erfolg dieser traditionellen Auswilderungen bisher kaum untersucht. Aus diesem Grund haben wir die ĂŒberlebensfĂ€higkeit von 62 mit Sendern markierten RothĂŒhnern unter zwei verschiedenen Auslassungsbedingungen untersucht. Im ersten Fall wurden die HĂŒhner jeweils an einer Stelle, im zweiten Fall an verschiedenen PlĂ€tzen im Auswilderungsgebiet freigelassen. DafĂŒr wurden die bei spanischen JĂ€gern und Jagdhegern ĂŒblichen Auslassungsmethoden imitiert. Die Null-Hypothese, daĂ es keinerlei Unterschiede zwischen den Ăberlebenschancen beider Klassen gebe, wurde abgelehnt (p = 0,019). In beiden Experimenten betrug die MortalitĂ€t in den ersten 72 Stunden nach der Auswilderung zwischen 25 und 34 %. Nach diesem Zeitraum war die ĂberlebensfĂ€higkeit der verteilt ausgelassenen RothĂŒhner signifikant besser als die der in einer groĂen Gruppe ausgewilderten Vögel, den ersten Monat ĂŒberlebten 37,4 ± 1,8 % der verteilt ausgelassenen im Vergleich zu nur 5,8 ± 1,1 % der an einem Standort freigelassenen HĂŒhnern (Abbildung). 37 von 39 TodesfĂ€llen waren mit hoher Wahrscheinlichkeit auf PrĂ€dation von Rotfuchs(Vulpes vulpes) und Steinadler(Aquila chrysaĂ«tos) zurĂŒckzufĂŒhren. Das traditionelle Verfahren zur Auswilderung von RothĂŒhnern in Spanien hat zur Aufstockung natĂŒrlicher Populationen wenig Wert. Dieses Verfahren kann jedoch durch Auslassung kleinerer Gruppen an verschiedenen PlĂ€tzen verbessert werden.[FR] Le lĂącher de perdrix rouges(Alectoris rufa) d'Ă©levage est de pratique courante dans les territoires de chasse espagnols. Bien que la production annuelle de perdrix rouges en voliĂšre atteigne quelque trois millions de perdreaux, l'efficacitĂ© de ces lĂąchers traditionnels n'a, jusqu'Ă prĂ©sent, guĂ©re Ă©tĂ© Ă©tudiĂ©e. C'est la raison pour laquelle nous avons analysĂ© le taux de survie de 62 perdrix rouges, marquĂ©es au moyen d'Ă©metteurs et lĂąchĂ©es selon deux procĂ©dĂ©s: dans le premier cas, les perdreaux ont Ă©tĂ© lĂąchĂ©s Ă partir d'un seul endroit, dans le second, Ă partir d'endroits diffĂ©rents. A cet effet, l'on a imitĂ© les mĂ©thodes courantes de lĂącher pratiquĂ©es par les chasseurs et par les gestionnaires de chasse espagnols. L'hypothĂšse 0, Ă savoir celle selon laquelle il n'y a pas de diffĂ©rence de taux de survie entre les diffĂ©rentes mĂ©thodes, a Ă©tĂ© repoussĂ©e avec p = .019. Dans les deux cas, la mortalitĂ© enregistrĂ©e au cours des 72 premiĂres heures aprĂs le l,cher se situait entre 25 et 34 %. Au terme de cette pĂriode, la capacitĂ© de survie des perdreaux lĂąchĂ©s en diffĂ©rents endroits s'est rĂ©vĂ©lĂ©e significativement supĂ©rieure Ă celle du lĂącher groupĂ©: ainsi, Ă la fin du premier mois, 37.4 ± 1.8 % des perdreaux lĂąchĂ©s Ă l'Ă©tat dispersĂ© survĂ©curent comparĂ©s Ă 5.8 ± 1.1 % seulement pour les perdreaux lĂąchĂ©s Ă l'Ă©tat concentrĂ© (Fig.). 37 des 39 cas de mortalitĂ©s Ă©taient plus que probablement Ă attribuer Ă l'action de prĂ©dateurs tels que le Renard(Vulpes vulpes) et l'Aigle royal(Aquila chrysaetos). La pratique traditionnelle du lĂącher de perdrix rouges en Espagne en vue de la reconstitution de populations naturelles nĂoffre que peu d'intĂ©rĂȘt. Cette pratique peut cependant ĂȘtre amĂ©liorĂ©e en lĂąchant de petits groupes de perdreaux en diffĂ©rents endroits.Peer reviewe