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The presence of parasitic Nematodes was determined by visual assessment of damage to the 271 weasel skulls (154 males and 117 females). The damages were attributed to Skrjabingylus nasicola (LEUCKART, 1842) or Troglotrema acutum (LEUCKART, 1842) (on the basis of it's appearance and relevant papers). The frequency of infestation by both parasites was 38%. It was higher in females and also increased along with age. A significant dependence between skull length of adult specimens and infestation rate was found.
The skull variability of Mustela nivalis Linnaeus, 1766 was studied with regard to age, sexual dimorphism and geographical distribution. The material consisted of 271 skulls from Poland. Linear dimensions of weasel skulls slightly increased with age. The changes in skull proportions were related to braincase diminution and increase in viscerocranium. In females, there was an obvious age variation in correlation structures which indicated synchronic growth and periods of stabilization. Sexual dimorphism was expressed by larger dimensions and different proportions in male skulls. The values of coefficients of variation were higher in males than females. Adult skull size was reached earlier by females than by male weasels. The correlation structures of male and female skulls were different. The skull dimensions increase from north-east to south-west Poland. It was revealed, that weasels from Poland but Silesia belong to the subspecies Mustela nivalis vulgaris Erxleben, 1777. Weasels from Silesia may probably form a separate subspecies Mustela nivalis trettaui Kleinschmidt, 1937.
The distribution and abundance of food resources is a major factor influencing animal populations. I studied the effect of a roe and red deer population decline on diet composition, home range size and foraging pattern in the Eurasian lynxLynx lynx (Linnaeus, 1758) in the Białowieża Primeval Forest (BPF), eastern Poland. The population of cervids in BPF experienced a nearly two-fold reduction in size from 1991 through 2006 due to severe hunting pressure between 1991 and 1996. Comparison of published data on lynx diet during the high abundance of ungulates with new data obtained for the low abundance period showed that despite a significant decline in their availability, cervids (roe and red deer) continued to form the majority of the diet of lynx, with roe deer being most preferred in both periods. Home range sizes of lynx showed a tendency to increase with declining prey densities, as indicated by relative percentage increases in average yearly home range sizes amongst different sex/age groups. In response to lower availability of their main prey, lynx increased their daily straight-line movement distances by 44% and doubled the ranges covered in 5-day periods. This illustrated that, with declining prey abundance, the lynx increased their hunting efforts by either spending more time actively searching for prey or continuing foraging even after a successful hunt. Spatial analysis of the distribution of ungulates and lynx indicated that deer were evenly distributed throughout lynx ranges in BPF and spatial proximity of the predator to prey sites did not play an important role in the efficiency of hunting. Lynx may adapt to changing prey availability by increasing search effort, but this was not sufficient to prevent the negative influences of the prey decline on the lynx population. Prey depletion has an immediate effect on lynx spatial organization and, in consequence, on their density. This information has to be considered in prioritizing lynx conservation measures and management of ungulates.
Lynx Lynx lynx maternal behaviour and dispersal pattern were studied by radio -telemetry in the Białowieża Primeval Forest, E Poland from 1992-1995. From June­-July, 2 females with kittens used 1-4 dens per month, for 5 to 33 days each, Consecutively used dens were 1-3 km apart and were located in inaccessible places. Female movements were concentrated around the den at this time, Mothers left their kittens and returned to them, on average, 3 times per day. Mean time of female's absence from the den was 4 h 20 min. Mean den attendance averaged 4 hours. In August, kittens began to accompany their mother. At this time, each den was used for 2-3 days only and the distances between consecutive dens were 0.5—2 km. Dens were situated in places where a female killed large prey. In August, a female spent an average of 12 h 50 min with kittens, alternating with 4-h of absence. Subadults dispersed at 9-11 months of age, immediately after separation from their mothers. Four subadult males dispersed for 11, 39, 62 and 129 km from their natal ranges. Two subadult females dispersed for 5 and 9 km. Lynx that moved the farthest distances covered most of their routes during the first two months of dispersal, when they moved 20-32 km/month, compared to 3-11 km/month in the later period. Distant emigrations of two adult lynx (55 km by a male and 120 km by a female) were also recorded. Directions and routes of lynx dispersal and emigration were related to the contemporary distribution and availability of woodlands and forest corridors.
Ryś jest w Polsce gatunkiem chronionym, ale bierna ochrona nie przyniosła dotąd zadowalających efektów. Zasięg występowania rysia zmniejszył się w północnowschodniej Polsce w ciągu ostatnich 20 lat. Ponieważ biologia rysia jest ściśle związana ze środowiskiem leśnym, podjęto próbę scharakteryzowania wybiórczości środowiskowej tego gatunku i określenia, jakie cechy otoczenia odgrywają rolę w ich podstawowych czynnościach biologicznych – polowaniu i odpoczynku. W tym celu przeanalizowano dane dotyczące charakterystyki środowiskowej miejsc odpoczynku i polowania rysi w Puszczy Białowieskiej uzyskane w trakcie badań telemetrycznych. Łącznie zlokalizowano 98 miejsc polowania i 80 miejsc odpoczynku 3 samców i 2 samic rysia oraz porównano je z opisem 81 miejsc losowych. W polowaniu szczególnie istotna okazała się duża liczba struktur ułatwiających podejście ofiary (zwalone pnie, wykroty, zarośla). Ważną rolę w polowaniu rysi odgrywały śródleśne polany z rozwiniętym runem i naturalnym odnowieniem z powodu ich atrakcyjności jako miejsca żerowania ssaków roślinożernych i dobrych warunków podchodzenia ofiar. Wykazano również, że miejsca zabicia ofiar charakteryzują się mniejszym zwarciem drzewostanu i większą widocznością niż miejsca ich późniejszego ukrycia. Miejsca odpoczynku charakteryzowały się gęstszym podszytem, większym zwarciem drzewostanu i niższym stopniem widoczności niż miejsca losowe. Młodniki były wybierane na odpoczynek częściej niż wynikałoby to z ich dostępności. Wyniki tych badań pokazują szczegółowe cechy środowiska, które zapewniają rysiom skuteczność polowania i bezpieczeństwo w trakcie odpoczynku. Na podstawie wymagań biologii rysia zaproponowano sposoby jego aktywnej ochrony poprzez odpowiednią restrukturyzację środowisk leśnych. Konieczność podjęcia takich działań jest szczególnie pilna na obszarach leśnych o uproszczonej strukturze lasu, które znajdują się w zasięgu potencjalnego występowania rysia w Polsce. Przebudowa struktury lasu w celu jej dostosowania do wymagań rysia może przyczynić się do zwiększenia jego liczebności, jak również do rozszerzenia zasięgu występowania gatunku.
Eurasian lynx is one of most widely distributed felid species. However, populations in central Europe are strongly fragmented and limited to forest areas, which may influence their sustainability and gene flow. We studied the edge effect on mortality of a highly isolated population of Eurasian lynx in the Białowieża Primeval Forest (NE Poland) during the 20-year period (1991–2011) of high economic development in Poland. Based on radio-tracking data collected in 1991–1996 (low gross national income per capita; low GNI PC) and 2004–2011 (high GNI PC) and recorded mortality cases, we analysed annual rates and causes of mortality and spatial distribution of death sites relative to the distance from the forest edge. We found significantly higher mortality of lynx during the low GNI PC phase of the economic growth than during high GNI PC (33 and 16 %, respectively). While anthropogenic factors played a dominant role in lynx mortality during low GNI PC, natural factors prevailed afterwards. We found a significantly higher proportion of lynx deaths than expected in the edge and outer zone than in the core of the Białowieża Forest. Both areas differ significantly in the proportions of mortality causes with anthropogenic factors being the main source of mortality in the outer zone. Our results indicate that the decline of lynx mortality in Poland could be related to the improving of the economic situation in the country after the collapse of communism and reduced significance of anthropogenic factors (mainly poaching). Additionally, the outskirts of the forest may function as population sinks, which may reduce the dispersal of lynx and gene flow between populations inhabiting different forest patches.
The home range size, spacing pattern and intraspecific relations in the lynx Lynx lynx (Linnaeus, 1758) were studied in Białowieża Primeval Forest (eastern Poland), in 1991-19S6. Eighteen lynx (11 males and 7 females) were captured and radio­-collared. The mean autumn-winter home range size was 165 km2 for males and 94 km2 for females. In spring-summer, it was 143 and 55 km2, respectively. The mean life-time home ranges were 248 km" for males and 133 km* for females. Male home range size did not change significantly between autumn-winter and spring-summer seasons, however, their ranges increased by 40-90% just before and during the mating season (December-March). The home range of females in the autumn-winter season was almost twice as large compared with the spring-summer period (94 vs 55 km2). The smallest home ranges were observed in breeding females during the two months after parturition (10 kmJ) and these grew until the following spring. The home ranges calculated for 5-month periods shifted on average 4 km in adult males, 2.7 in adult females and 4.7 km in subadult males. One of the farthest shifts in the adult male range (8.7 km) was explained by the death of a neighbouring resident. The average overlap between adult males' ranges was 30%, while those between females was 6%. The largest overlap occurred between adult males and females (62%) as well as between adult and subadult males (75%). The lynx showed a tendency to avoid each other. The average distance between neighbouring adult males was 11.6 km, and they were never found closer than 1 km to each other. The average distance between neighbouring females was 8.1 km. Besides a few meetings between males and females (during and outside the mating season), they were located separately (4.4 km from each other, on average), in 93% of the cases an adult female was recorded with her dependent kittens. It was concluded that home range size and spacing pattern in male lynx depend on the distribution of females, whereas spacing in females was determined by food-related factors.
Material. Thirty eight fecal samples of Eurasian Lynx (Lynx lynx L.) collected in Białowieża Primeval Forest (E Poland) in years 2001-2004 were analysed. Results. The presence of Aelurostrongylus abstrusus (L1) larvae was evidenced by use of decantation and flotation methods. The general prevalence of the infection recorded during the study was 21.1%, whereas mean intensity was 11,5 (1-33 larvae per sample). To our knowledge, this is the first case of Aelurostrongylus abstrusus recorded in Euroasian lynx from Poland.
We studied microhabitat selection of the Eurasian lynxLynx lynx (Linnaeus, 1758) at 116 hunting and 88 resting sites in Białowieża Primeval Forest (Poland) to describe its characteristics and determine the importance of habitat structure for stalking prey and for security during resting. We identified lynx-used sites by radio-tracking 3 male and 3 female lynx. When hunting, the lynx did not select for any type or age class of forest. During both summer and winter, the lynx selected sites characterized by high complexity (number of structures useful for stalking: fallen logs and branches, root plates, patches of dense bushes) and low visibility. In summer, hunting sites were often located in the vicinity of small forest glades that provided good stalking opportunities for lynx and rich foraging resources for roe deer — the main prey of lynx. The habitat at kill sites was more open than at sites where the prey was cached, with higher visibility, lower density of trees and poorer undergrowth. The most important characteristic of resting sites was very low visibility that resulted mainly from using young pine or spruce thickets in the winter and dense undergrowth of oak-lime-hornbeam and ash-alder forests in the summer. The information provided by this study could have direct implications for Eurasian lynx conservation by guiding forest restructuring to better suit the species’ biological requirements.
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