![]() In addition, falcons are obligate users of white-headed buffalo weaver nests therefore, they experience all of the benefits these nests provide without the energetic cost of building or maintaining them. Weavers also do not maintain these nest chambers occupied by falcons, increasing the likelihood that these particular chambers will break off the main colony. However, falcons appear to have a preference for chambers away from the center of the colony and with shorter entrance tunnels. Although it is likely that falcons would benefit from selecting chambers with better insulation, they are larger than weavers and as a result may struggle to access chambers through longer entrance tunnel. Pygmy falcons mark their nests by the use of their faecal matter, but the reasons behind this is unknown. It has been suggested that this conspicuous faecal mat (white when fresh and turning pinkish with age) present at the entrance of the chamber could deter snakes and reduce the number of ectoparasites. Faecal matter is also though to boost the immune system of chicks as well as signal to conspecifics. however, because artificial nests produced more fledglings, we found that overall productivity of juveniles to dispersal at artificial and natural nests sites did not differ significantly.Faecal mats at the entrance of occupied chambers may serve as a social signal to indicate to other falcons that a colony is occupied. Predation was identified as a major cause of mortality, especially in open landscapes where artificial nests were located. Over the PfDP, the best-fitting model to explain juvenile survival incorporated fledging date and nest site type, with juvenile survival being higher in early fledged broods from natural sites. Duration of the PfDP was estimated as 40 days (range: 31-52 days). natal home ranges were larger for juveniles fledged at artificial than natural sites and the distance moved by juveniles during PfDP was positively related to fledging date and brood size. During the post-fledging dependence period (PfDP) juveniles progressively moved farther from their nest until dispersal from the natal area. SUMMArY.-We used patagial tags, vhf radio transmitters, and satellite-received transmitters to investigate the movements and survival of juvenile saker falcons fledged from artificial nests in open landscapes and natural nest sites in hilly areas in Mongolia. Future studies should include this aspect by the use of a thermal-imagery camera in addition to regular video camera. I was unable to decide whether some of the prey items delivered at the nest had been retrieved from caches, so the time of delivery was not necessarily shortly after capture for all prey. Handling time increased with body mass of the prey, both when the female assisted in feeding the nestling and when the nestling fed unassisted. ![]() The nestling required maternal assistance in feeding until it was 29 days old. The probability that a prey item was decapitated before delivery was lower if the prey item was a thrush than when it was another kind of bird, and decreased with nestling age. The probability that a prey item had been plucked prior to delivery at the nest decreased with increasing prey body mass when the nestling fed unassisted, but not when the female fed the nestling. Outside the nest, I observed the male was delivering some prey items to the female, whereas the female dismembered the prey and fed the nestling. The female was recorded to deliver the majority of prey (95%) at the nest, whereas the male started to deliver prey items directly at the nest from when the nestling was 30 days old. The probability of delivering a thrush rather than a small passerine was low in the morning and the evening, and high near midday. The probability of delivering a prey item at the nest was highest during morning and evening, and lowest around midday. Woodpigeons (Columba palumbus) made up only 6.8% by numbers and was the next most important prey type by net body mass delivered (29.2%). Small and larger passerines pooled was the next most important prey type by number (39.8%), but contributed little (9.8%) by net body mass. The most important prey type were thrushes (Turdus sp.), by both numbers (47.7%) and net body mass delivered (57.1%). A total of 88 prey items were recorded delivered, all of which were birds. The study was conducted from the single nestling was 10 days old until it fledged. The diet, diel pattern of prey deliveries, and prey handling behaviour of a nesting pair of the peregrine falcon (Falco peregrinus) in southeast Norway was studied with video recording equipment at the nest and direct observations of parental behaviour and interactions in the vicinity.
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