|
| |
|
|
Chemical communication in field mice of the genus ApodemusApodemus
Obstová, Lucie ; Stopka, Pavel (advisor) ; Vohralík, Vladimír (referee)
The bachelor thesis deals with a special sebaceous organ that probably serves as a chemical communication means with four species of Apodemus field mouse - A. flavicollis, A. sylvaticus, A. agrarius and A. microps. This organ is found on the ventral side of a tail, so it is classified as a caudal organ. It consists of significantly enlarged sebaceous glands. It is particularly developed mainly with males; however, both females and infants have it as well. Its morphological structure has the same base regardless of the species, gender, and/or age; however the extent of development varies among species. The organ releases a secretion whose chemical content is unknown so far. Thanks to the gas-liquid chromatography, researchers have found out that there are both variations in the secretion contents among individual species, as well as within the same species. This kind of secretion is basically a characteristic feature of an individual, as it bears information about the species, gender, age and even the population affiliation. Functions of the organ stay unknown as well. It might serve to mark the territory, to play a role in social interactions (i.e. agonistic behaviour) and/or to be an important part of copulatory behaviour.
|
|
|
American mink (Neovison vison) - biology of an invasive species.
Hlaváčová, Petra ; Vohralík, Vladimír (advisor) ; Anděra, Miloš (referee)
The American mink is considered to be an invasive, alien species across Europe, North Asia and also in South America and now it is perceived as a permanently growing treat for native biodiversity. Mink is an extremely adaptable predator, which achieves to adapt to almost any conditions and different food niches. The aim of this study was to contribute to cognition of biology of this species in Czechomoravian highlands condition. A telemetry study was run between 2004 and 2012 during which in total six individuals (3 males and 3 females) were being monitored on the Sázava River near Havlíčkův Brod. This study was supplemented by usage of photo traps. A couple of finding can be drawn from this study. Mainly, the records show the significant differences between sexes. Males and females differ in home range size, in day/night activity and in length of day movements. The second part of this study was focused on distinguishing tracks of three different species of mustelids: American mink, European mink and Western polecat. In total, 211 tracks obtained from these three species were measured. Seven points on a track has been identified, and the computer program Measuring tracks automatically created 131 parameters. These parameters were processed with canonical discriminant analysis. The results showed...
|
|
|
Craniometric study of Central European populations of the white-toothed shrews Crocidura suaveolens and C. leucodon (Mammalia: Soricomorpha)
Milerová, Petra ; Vohralík, Vladimír (advisor) ; Anděra, Miloš (referee)
Interspecific and intraspecific size variability of the skull, mandibles and teeth of the lesser white- toothed shrew Crocidura suaveolens and the bicolored white-toothed shrew C. leucodon was studied on material of 350 skulls and 465 mandibles of white-toothed shrews obtained by analysis of the barn owl pellets originating from four regions in the Czech Republic and one region in the southern Slovakia. C. suaveolens was present in all regions under study, while sympatric C. leucodon occurred in three regions only. In total, 21cranial and dental measurements and 4 mandibular measurements were investigated. It was found that the most reliable measurement enabling discrimination between skulls of both species in the whole studied material is the lenght of the lower dental row. If skulls of both species were evaluated separately for each area of their sympatry it was possible to use also the distance between second molars M2 and the width of premolar P4 . Skulls of these two species can also be distinguished by bivariate graphs using the length and width of premolar P4 and the palatal length. We studied relationships between cranial measurements of both species and geoclimatic factors such as longitude, latitude, mean annual temperature and mean annual percipitation. It was found that variability of...
|
|
|
Vigilance and escape behaviour in ground squirrels (tribe Marmotini)
Milerová, Petra ; Vohralík, Vladimír (advisor) ; Matějů, Jan (referee)
In the ground squirrels, vigilant antipredator behaviour is frequently studied as a part of antipredator strategy. More vigilant animals have greater chances to avoid a predator attack. But it's also true, that animals allocating more time to vigilance, can allocate less time to foraging. There is obvious trade-off between vigilance and foraging. Ground squirrels, marmots and prairie dogs have to receive a lot of food to accumulate fat reserves for the hibernation period, and in case of juveniles also to ensure their growth. Therefore, they are forced to allocate time between aforementioned activities suitably. In view of the close relationship between vigilance and foraging, these two activities are often investigated together. The most important factors influencing aforementioned activities are number of simultaneously active individuals and presence of visual barriers. An affect has also age, sex and reproductive status of the individual or caloric content of the food. After the detection of a predator with the aid of vigilance, can be initiated escape response. Escape distance, escape velocity and escape behaviour in general are influenced especially by the type of predator, type of vegetation cover and individual distance from a burrow entrance. It is important that total energy costs of these...
|
|
|
Acoustic communication in two species of ground squirrels Spermophilus citellus and S. taurensis (Sciuridae; Rodentia).
Schneiderová, Irena ; Vohralík, Vladimír (advisor) ; Petrusková, Tereza (referee)
6 ABSTRACT Since now, acoustic communication and alarm calls of European ground squirrel and the recently described S. taurensis have been poorly studied. Aim of this study is to make first steps in studying and understanding their acoustic communication and alarm calls. It was found, that the European ground squirrel produces 6 vocal (growl, rapid growl, scream, squeak, chirp, whistle) and 1 nonvocal (tooth chatter) sounds. These sounds are produced when sousliks are directly threatened by predator or during their social contacts. The alarm call of European ground squirrel as well as of S. taurensis is the whistle. It usually consists of two different elements, which can be fused, overlapped in time or separated by short interval. The first element has a constant frequency, while the second one has little frequency modulation. In some cases, one of these elements can be missing. The study reveals individual variation in the alarm calls in both species. Sexual differences in alarm calls of S. taurensis were found. Keywords: Spermophilus citellus, Spermophilus taurensis, Sciuridae, ground squirrel, antipredator behaviour, acoustic communication, vocalization, vocal repertoire, alarm call.
|
|
| |
|
| |
|
| |
|
|
Acoustic communication and its variability in selected populations of ground squirrels of the genus Spermophilus
Schneiderová, Irena ; Vohralík, Vladimír (advisor) ; Sedláček, František (referee) ; Špinka, Marek (referee)
The thesis deals with vocalizations produced by Eurasian ground squirrels of the genus Spermophilus. It is mainly focused on inter-species and intra-species variability in acoustic structure of alarm calls which are emitted in presence of predators.The major part of the thesis deals with intra-species variability in acoustic structure of the alarm calls in five Eurasian ground squirrels, Spermophilus citellus, S. taurensis, S. xanthoprymnus, S. suslicus and S. fulvus. It has been confirmed that the alarm calls of these ground squirrels show a high level of species specificity. The thesis further describes another vocalizations produced by three Eurasian ground squirrel species, Spermophilus suslicus, S. citellus and S. fulvus, and shows that with the exception of the alarm calls, vocal repertoires of these three ground squirrels are remarkably similar. The last part of the thesis deals with individual distinctiveness of the alarm calls of three Eurasian ground squirrels, Spermophilus citellus, S. taurensis and S. xanthoprymnus. It has been shown that the alarm calls of these species have a significant potential to encode information about caller identity.
|
guest ::
