• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1
  • Tagged with
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Organisation & development of anti-predator behaviour in a cooperative breeder

Westrip, James Robert Samuel January 2016 (has links)
In order to reduce their predation risk, species have evolved a range of anti-predator behaviours. One co-ordinated anti-predator behaviour present in some group-living species is sentinel behaviour. In this behaviour individuals take up an elevated position and scan for threats, providing an alarm when one is spotted. However, this behaviour can lead to social conflict. Sentinel behaviour is a public good, i.e. the benefits are felt by all group members, but the costs only accrue to the actor. Thus it may be open to free loading, requiring individuals to monitor collaborators to prevent cheats. Additionally, individuals may vary in their alarm call reliability, which may select individuals to alter their behaviour based on caller ID. Monitoring others requires individuals to be closely associated, yet individuals may be spread out. For instance, foraging groups may be some distance from their nest, yet nestlings are particularly vulnerable. Adults should reduce their number of nest visits if a threat is nearby, so individuals returning from the nest may be selected to communicate about any perceived threats. Additionally, when perceiving threats, species need not use only conspecific information, because heterospecifics can also provide relevant information. In this thesis, I test these ideas in the Southern Pied Babbler (Turdoides bicolor), and I show that a) pied babblers monitor the quantity and quality of group-mates’ anti-predator behaviour; b) babblers accompany naïve sentinels and I investigate whether this may be related to anti-predator teaching; c) babblers do not appear to actively communicate about perceived nest threats because they do not alter their provisioning rate based on heterospecific derived anti-predator information; while d) avian heterospecifics are more prevalent in the presence of pied babblers, and can be attracted to areas by playback of pied babbler calls. These results show that species monitor both conspecifics and heterospecifics, and alter their behaviour based on the information they collect.
2

Výsledky hnízdění a odchovů jednotlivých druhů sojkovců (Timaliidae, Passeriformes) v zoo Praha / Results of nesting and breeding of some species of birds Family (Timaliidae, Passeriformes) in the zoo Praha

JANDOVÁ, Ivana January 2014 (has links)
Babblers together with the close related Timallidae are not very common inmates of the zoological gardens. In the Czech Republic they are only bred in the zoological gardens in Ohrada, Pilsen and Prague. The breeding in the zoological gardens is not generally very successful. The zoo in Prague with its number of species owns the largest collection of these birds in Europe. In the past the breeders in Prague were the first ones in Europe who managed to raise for example Rufous-fronted Laughingthrush, Sunda Laughingthrush, Barred Laughingthrush or Sumatran Laughingthrush (Black-and-white Laughingthrush). As the first ones in the Czech Republic they were able to reproduce the critically endagered Blue-crowned Laughingthrush (Courtois's Laughingthrush). The Blue-crowned Laughingthrush is so rare that for several years it was not clear at all if they still live in nature. In the year 2000 they were rediscovered in the number of 240 pieces. The quantity of them in the zoological gardens all over the world does not exceed 100 pieces. The zoo in Chester does a European breeding book of these pieces. Some birds in Prague reproduce repetitively and they prove that the right method of the breeding was found. Hopefully this method would lead to the birth of the securing population in the care of humans. This securing population is very important for the protection of these birds. The attempt of this work is to assess the links between the results of the breeding and their conditions, the comparison of the nesting activities of the two chosen species of babblers, then the summarizing of the expansion and the results of the breeding of the individual species and also the processing of the expansion, the development of the quantity and the problems of the protection of the babblers in nature. The following facts were found out: the breeding of the birds in the exposition or in its environment does not have an essential influence on their nesting activity. However, for the nesting activity it is more important if they are a newly formed couple or a couple paired for a longer time and at the forest babbler it is the female that has an important role in incubation period. However, at the Sumatran Laughingthrush there is a frequent changing in different time intervals. The work also shows that only 5 species out of 12, that showed the nesting activity, are able to build a nest without the help of the keepers. That can be attributed to their closer relational breeding and also to putting the higher number of artificially reared individuals into the breeding.

Page generated in 0.0506 seconds