Małgorzata Krasińska

Body mass and measurements of the European bison during postnatal development

Body mass of the European bisonBison bonasus (Linnaeus, 1758) was determined for 152 animals (86 males, 66 females) from captive breeding centre in Białowieża and for 492 (248, 244) animals from the free-ranging herd in the Białowieża Forest. Body measurements were taken for a total of 472 bison (204, 268). Age-related changes in body mass and measurements of 375 bison (165, 210) were analysed. Bison body mass was significantly correlated with age. Captive bison were heavier than those from a free-ranging herd. Measurements showed the changes in bison body structure in the postnatal development. All measurements were highly correlated with age and mass of the animals and increased most intensively during the first year of life. Sex-related differences in body mass and measurements were most pronounced in bison ≥ 3 years old. Physical development of females ends at the age of 5 years, and that of males at the age of 7 years.

Movements of European bison (Bison bonasus) beyond the Białowieża Forest (NE Poland): range expansion or partial migrations?

The European bison is the largest terrestrial mammal in Europe. After extinction in the wild at the beginning of the twentieth century, it was re-introduced to Białowieża Forest and other woodlands in Eastern Europe. In this paper, we analysed the movements of European bison beyond the continuous woodlands of the Białowieża Forest (NE Poland) between 1964 and 2010. In total, 1,117 direct observations of bison were collected. The number of males moving out of the forest fluctuated during the study period, whilst the number of females steadily increased. The number of male observations outside of the forest per annum was dependent on the population size and snow depth, whilst the number of cows in mixed groups moving outside of the forest was correlated with the population size only. Males were observed mainly alone (50xa0% of observations) or in small groups of two to three individuals (25xa0%); however, distribution of group size differed from those observed in the population. There was a significant difference between the direction of movement of males and females out of the forest—males moved mainly west and southwest, whilst females moved to the north. This was also significantly different from the expected movement direction. The mean distance of bison observations from the forest border was 1.8u2009±u20090.13xa0km and did not differ significantly between sexes. After 1990, males were observed significantly farther away from the forest (2.2xa0km) than in the previous years (0.9xa0km). Most observations (94xa0% of bulls and 93xa0% of cows) were up to 5xa0km from the forest edge. The range of bison in the vicinity of the Białowieża Forest was strictly seasonal. Most observations (78xa0% in males and 88xa0% in females) were recorded from November to April. Increasing utilisation of areas beyond the forest habitats may be driven by different factors but most probably it is related to range expansion and the bisons preference for open habitats. The strong seasonal pattern of bison movements indicate that the partial seasonal migrations were initiated in the Białowieża population.

Has the condition of European bison deteriorated over last twenty years

Twelve biochemical values of the serum (concentrations of sodium, potassium, calcium, glucose, urea nitrogen, creatinine, total protein, and enzyme activities of ALP, CPK, AspAT, AlAT, amylase) were determined for 102 bisonBison bonasus (Linnaeus, 1758) coming from the free-ranging population of the Białowieża Forest and from the breeding enclosure. The animals were culled in the winter periods of 2000/2001 and 2002/2003. In adult males only the activity of AlAT is significantly higher than in adult females. The remaining values do not differ significantly between the sexes in any of the three age groups (I—calves, II—youngsters, III—adults). Also, no significant differences in serum parameters were observed between healthy males and the ones exhibiting symptoms ofposthitis/balanoposthitis. It was established that the following changes in the values of serum parameters are age-dependent: a decrease in potassium and glucose concentrations and the enzymatic activity of ALP, and an increase in AspAT activity. The results were compared to the corresponding data from the research carried out 20 years earlier (1980–1984) and it has been discovered that the values of seven parameters are significantly different as opposed to the previous results. The following differences were established: currently the concentrations of potassium and urea nitrogen are higher in all age groups; the concentration of glucose is higher in the groups of calves and youngsters; creatinine concentration is lower in adults; the activity of AspAT has increased in youngsters, only; the activity of AlAT has increased, and of amylase has decreased in all animals examined. The changes in the values of serum parameters were analysed in the context of data obtained from post-mortem examinations and we conclude that those changes reflect the growing number of pathomorphological changes in internal organs of the bison dissected. Changes localised mainly in the liver and lungs could be related to parasitical infestations; others were noted in kidneys and in the prepuce and penis area in the males withposthitis/balanoposthitis symptoms. In the discussion it is suggested that the deterioration of the physical condition of European bison inhabiting the Białowieża Forest may be connected to such environmental and populational factors as: winter supplementary feeding, winter aggregations, and a decline in immunity related to inbreeding.

Accuracy of radio-tracking to estimate activity and distances walked by European bison in the Bialowieza Forest, Poland

To determine the accuracy of radio-tracking estimates of activity and distances walked by European bisonBison bonasus (Linnaeus, 1758), we observed bison while simultaneously conducting radio-tracking in the Bialowieża Forest (Poland). Single radio-tracking estimates often did not represent the actual activity of the bison, but the mean time spent active calculated from radio-tracking and direct observations did not differ significantly. Radio-tracking provided overestimates of the distances walked by bison when the animals walked between 0 and 25 m and underestimated the distances walked by bison if they walked further than 25 m in a radio-tracking interval. Activity was best estimated when radio-trackers were between 200 and 300 m from the bison. The mean activity calculated with a sampling interval of 15 min needed about 8 days of radio-tracking and the mean of distances walked about 35 tracking days to stabilise. We concluded that collars without activity sensors can measure the mean activity of bison but cannot represent the length of their activity bouts or the type of their activity and that our radio-tracking estimates of distances walked by bison needed to be corrected before further analyses.

Changes of weight and size of European bison testes during postnatal development

The material for this study was obtained from culled European bison (Linnaeus, 1758) originating from both captive breeding and free-ranging populations in Białowieża and Borecka Forests (north-east Poland), and was mostly collected from November until April. Mass difference between the right and left testis of the same individual up to 30% was considered to be physiological asymmetry, which proved typical of the species. Hypoplasia or atrophy of the testes exceeding 30% in size, were found in 37 males (13.6% of the examined animals;n=272). Cryptorchidism was recorded in 20 bison culled in Białowieża Forest at the age over 1 year (10.6% of individuals at the same age;n=188). We registered the weight of testes of 259 males aged 2 months to 20 years. In the examined males, no distinct predominance in size and weight between the right and left testes was observed. The weight of testes was significantly correlated with age (r=0.85,p < 0.0001) and body weight (r=0.93,p < 0.0001). The heaviest testicles belonged to older and sexually mature bulls aged 6–12 years (mean 216 g) and to old ones over 13 years (mean 242 g). Two testis measurements (length and width) were taken from 136 culled males, while two additional measurements (total length with the cauda of epididymis and circumference) from 65 males. The length and width of the testes were moderately correlated with age (r=0.31 andr=0.20,p < 0.01) and highly significantly correlated with testis (r=0.79,p < 0.001) and body weight (r=0.92,p < 0.001).

Polymorphism of bovine microsatellite DNA sequences in the lowland European bison

Investigations of genetic polymorphism of microsatellite DNA sequences were conducted in 22 individuals of the European bisonBison bonasus (Linneaus, 1758) from Białowieża Primeval Forest. For this purpose 27 cattle microsatellite primer pairs were used. Among the 27 microsatellite markers examined, an amplification product was obtained for 21 loci. This rendered it possible to identify total of 40 alleles in the bison population tested. In addition, eight loci were proved to be monomorphic. A majority of the 40 alleles identified was identical with the alleles identified at the corresponding loci in cattle. Only two alleles seem to be specific for the European bison. The value of heterozygosity for the examined loci in bison population from Białowieża was low and ranged from 0.13 to 0.53. Hence, the polymorphism information content was low as well. Based on our results the microsatellite DNA markers identified in cattle may be used to analyse the genetic structure of the population of European bison.

Cases of spermiogenesis in young European bison

Development of spermiogenesis and sizes of seminiferous tubules of the testes and epididymal duct were studied in 45 young European bisonBison bonasus (Linnaeus, 1758) males from an enclosed breeding centre and a free-ranging population in the Białowieża Forest. Of 13 males in age class II (up to two years), four showed the presence of elongated late spermatids: one male aged 15 months from the enclosed breeding centre and three from the free-ranging population (2 males aged 18 months and one about 24 months old). Of 7 males from age class III (up to 3 years), four showed spermiogenesis, of which the youngest, 26 and 32 months old, were from enclosed breeding. Spermiogenesis was observed in males with high body weight in a given age class. In males of age class I (up to one year old), the mean diameter of the seminiferous tubules was 49.8 μm, in class II — 110.7 μm, and in class III — 162 μm, the mean diameter of the epididymal duct being 110.8 μm, 187.2 μm and 273.4 μm, respectively. Measurements of seminiferous tubules and epididymal duct were significantly correlated with age and body weight of males and differed significantly between the three age classes.

Morphometric variation of the skull during postnatal development in the Lowland European bisonBison bonasus bonasus

We studied the variation of linear measurements and skull capacity in Lowland European bisonBison bonasus bonasus (Linnaeus, 1758) during postnatal development, and the dependencies of the parameters in relation to sex, age, and body mass of the animals. Material consisted of 599 bison skulls (310 males and 289 females), within the age range of 1 month to 21 years (males) and to 27 years (females). In the group of calves to 1 year old, no sex connected differences in skull measurements were observed, whereas the skull capacity in older calves was significantly larger (0.01>p>0.001) in males than in females. From the third year of life, most skull measurements display characteristics of sexual dimorphism. Skull development in both sexes is most intensive during the first three years of life, and slows from the age of 5. In older individuals of both sexes (≥ 6 years), orbital breadth continues growing and, in females, breadth of splanchnocranium continues increasing. Growth in a bison’s skull capacity is most intensive up to the third year of life and slows from the age of 5. During postnatal development, a bison skull grows proportionally except the neurocranium, which grows slightly slower in comparison with basal length and its development finishes earlier than that of splanchnocranium. In ontogenesis, a bison skull grows much slower compared to body mass. In relation to body mass, skull capacity and the height of neurocranium grow most slowly while orbital breadth grows most intensively. The results obtained were compared with data on skull sizes of bison born in 1930–1950 and bred in captivity and with skulls of the American bisonBison bison. Inbreeding is probably responsible for some types of phenotypic abnormalities in the skull which appear in modern European bison.

Sexual dimorphism in skulls of the lowland European bison, Bison bonasus bonasus

The research was conducted on 600 (311 male and 289 female) European bison skulls of the Lowland line collected between 1967 and 2006. The specimens came from the bison breeding centre in Białowieza (n = 67) and from the free-ranging population of the Polish part of the Białowieza Forest (n = 533). Two indices best differentiating male and female skulls were selected: one being the quotient of the orbital breadth EctEct and the length of the splanchnocranium StP, the second being the quotient of the neurocranium length BSt and the basal skull length BP. Using these indices we constructed an equation which produced negative values for females and positive values for males; 223 (74%) of the male skulls produced positive values consistent with sex, and 82 (26%) produced negative values, indicating female features. Those features were present mainly in skulls of young males (< 4 years old). 230 (80%) of the female skulls had shapes typical of the female sex, whereas 59 (20%) displayed male features.

Bisoniana 104. Shape of the mandible in European bison and domestic cattle hybrids

The shape of the mandible of European bison and domestic cattle hybrids and the parental forms was compared by means of a discriminant function. In most cases it was observed that the mandibles of hybrids of backcross generations are similar or identical to cattle. Exceptions were found in F1 hybrids and some backcross generations whose mandibles were more similar to bison than to cattle. The transformation of the mandible shape in hybrids with increasing cattle genes is similar to changes in the skull shape of the same animals.