Stadt und (Jugend-)Kultur: Jugendliche als Zielgruppe und Akteure städtischen Wandels

'Im Zuge der sozialen Aufwertung innenstadtnaher Wohngebiete und Konsumzonen in europäischen und US-amerikanischen Städten in den letzten beiden Jahrzehnten werden städtische Konsum-, Freizeit- und Kulturangebote zunehmend auch auf ein jugendliches und jung-erwachsenes Publikum hin ausgerichtet. Jugendliche profitieren also in gewisser Hinsicht von gegenwärtigen Prozessen städtischen Wandels. Die (Wieder-) Eroberung und Belebung von öffentlichem Raum durch Jugendliche erfolgt aber auch durch jugendkulturelle Präsenz in den Straßen (z.B. durch Streetpartys) oder Straßensport (Inline Skaten, Skate Boarden, Street Basketball). Eine negative Konsequenz der kulturellen und ökonomischen Aufwertung von Stadtgebieten bzw. ihrer kulturellen Ausrichtung auf ein junges Publikum ist jedoch, dass einkommensschwächere StadtbewohnerInnen sowohl aufgrund steigender Mietpreise in den Innenstadtgebieten als auch kulturell an den Stadtrand verdrängt werden. Vor allem künstlerische Avantgarde, Kulturindustrie und Jugendkultur spielen in diesen Verdrängungsprozessen nicht selten sogar eine Pionierfunktion. Zunehmend ausgeschlossen werden aber auch unerwünschte Gruppen wie Obdachlose, Bettler oder marginalisierte/ unangepasste Jugendliche, die dem Klischee der sauberen und sicheren Stadt widersprechen.' (Autorenreferat

Parental food provisioning and nestling growth under Philornis downsi parasitism in the Galapagos Green Warbler-Finch, classified as 'vulnerable' by the IUCN.

In the Galapagos Islands, many endemic landbird populations are declining due to habitat degradation, food availability, introduced species and other factors. Given nestlings typically lack efficient defense mechanisms against parasites, hematophagous ectoparasites such as the larvae of the introduced Avian Vampire Fly, Philornis downsi, can impose high brood mortality and cause threatening population declines in Darwin finches and other landbirds. Here, we assess whether the food compensation hypothesis (i.e., the parents' potential to compensate for deleterious parasite effects via increased food provisioning) applies to the Green Warbler-Finch. We differentiated nests with low or high infestation levels by P. downsi and quantified food provisioning rates of male and female parents, time females spent brooding nestlings, and nestling growth. Male provisioning rates, total provisioning rates and female brooding time did not significantly vary in relation to infestation levels, nor by the number of nestlings. Opposed to the predictions of the food compensation hypothesis, females showed significantly reduced provisioning rates at high infestation levels. Nestling body mass was significantly lower and there was a reduction of skeletal growth, although not significantly, in highly infested nests. The females' response to high infestation may be due to parasites directly attacking and weakening brooding females, or else that females actively reduce current reproductive effort in favor of future reproduction. This life-history trade-off may be typical for Darwin finches and many tropical birds with long lifespans and therefore high residual reproductive value. Conservation strategies may not build on the potential for parental food compensation by this species

Invasive parasites habitat change and heavy rainfall reduce breeding success in Darwin's finches

Invasive alien parasites and pathogens are a growing threat to biodiversity worldwide, which can contribute to the extinction of endemic species. On the Galápagos Islands, the invasive parasitic fly Philornis downsi poses a major threat to the endemic avifauna. Here, we investigated the influence of this parasite on the breeding success of two Darwin's finch species, the warbler finch (Certhidea olivacea) and the sympatric small tree finch (Camarhynchus parvulus), on Santa Cruz Island in 2010 and 2012. While the population of the small tree finch appeared to be stable, the warbler finch has experienced a dramatic decline in population size on Santa Cruz Island since 1997. We aimed to identify whether warbler finches are particularly vulnerable during different stages of the breeding cycle. Contrary to our prediction, breeding success was lower in the small tree finch than in the warbler finch. In both species P. downsi had a strong negative impact on breeding success and our data suggest that heavy rain events also lowered the fledging success. On the one hand parents might be less efficient in compensating their chicks' energy loss due to parasitism as they might be less efficient in foraging on days of heavy rain. On the other hand, intense rainfalls might lead to increased humidity and more rapid cooling of the nests. In the case of the warbler finch we found that the control of invasive plant species with herbicides had a significant additive negative impact on the breeding success. It is very likely that the availability of insects (i.e. food abundance) is lower in such controlled areas, as herbicide usage led to the removal of the entire understory. Predation seems to be a minor factor in brood loss

Did tool-use evolve with enhanced physical cognitive abilities?

The use and manufacture of tools have been considered to be cognitively demanding and thus a possible driving factor in the evolution of intelligence. In this study, we tested the hypothesis that enhanced physical cognitive abilities evolved in conjunction with the use of tools, by comparing the performance of naturally tool-using and non-tool-using species in a suite of physical and general learning tasks. We predicted that the habitually tool-using species, New Caledonian crows and Galápagos woodpecker finches, should outperform their non-tool-using relatives, the small tree finches and the carrion crows in a physical problem but not in general learning tasks. We only found a divergence in the predicted direction for corvids. That only one of our comparisons supports the predictions under this hypothesis might be attributable to different complexities of tool-use in the two tool-using species. A critical evaluation is offered of the conceptual and methodological problems inherent in comparative studies on tool-related cognitive abilities

Nuthatch uses tool in London park

Funding: manuscript preparation was supported by BBSRC grant BB/G023913/2 (C.R).Here, we report an observation of a Eurasian nuthatch Sitta europaea foraging with a tool in a public park in Greater London, UK. This record is of significance, as it provides the first photographic evidence (to our knowledge) of nuthatch tool use, reveals an unusually wide phylogenetic and geographic distribution of tool behaviour within the Sittidae, and constitutes a rare example of animal tool use in an urban environment. To improve our understanding of nuthatch tool behaviour, we are building a global database of relevant anecdotal field observations—submissions are most welcome.PostprintPeer reviewe