Wichmann G.,BirdLife Austria
Acta Zoologica Bulgarica | Year: 2011
After being extinct for nearly 200 years, the Eastern Imperial Eagle (Aquila heliaca Savigny 1809) returned to Austria in 1999. By 2009, the population has increased to reach 4-5 breeding pairs. The main habitats of the Eagles include agricultural steppe areas, as the most common prey species are Hare (Lepus europaeus Palls 1778), Common Pheasant (Phasianus colchicus Linnaeus 1758), European Hamster (Cricetus cricetus Linnaeus 1758), and Feral Pigeon (Columba livia f. domestica Gmelin 1789). The breeding success amounts to 1.63 juveniles/started brood. The reasons for chick mortality are mostly human disturbance, bad weather or a combination of both.
Dvorak M.,BirdLife Austria |
Fessl B.,Charles Darwin Foundation |
Nemeth E.,Konrad Lorenz Institute |
Nemeth E.,Max Planck Institute for Ornithology (Seewiesen) |
And 2 more authors.
ORYX | Year: 2012
Population monitoring is a vital tool for conservation management and for testing hypotheses about population trends in changing environments. Darwin's finches on Santa Cruz Island in the Galápagos archipelago have experienced habitat alteration because of human activity, introduced predators, parasites and disease. We used point counts to conduct systematic quantitative surveys of Darwin's finches and other land birds between 1997 and 2010. The temporal analysis revealed that six of the nine species investigated declined significantly and that this decline was most pronounced at higher elevations in humid native forest and agricultural areas; the highland areas have been most affected by introduced species or direct human impact. Five of the six declining species are insectivorous, which suggests that changes in insect abundance or insect availability are a critical factor in the declines. Further study is required to test this idea. Other factors including habitat alteration and introduced parasites or pathogens may be contributing to the observed declines. © 2012 Fauna & Flora Internationa.
Rossler M.,University of Natural Resources and Life Sciences, Vienna |
Nemeth E.,BirdLife Austria |
Bruckner A.,University of Natural Resources and Life Sciences, Vienna
Biologia (Poland) | Year: 2015
To prevent birds from collisions with glass, markings on glass panes can be a valuable measure. However, to ensure public acceptance and widespread use of glass markings, maximum deterrent effect at minimum area covered has to be achieved. In this study we show that the efficacy of a deterring pattern does not necessarily depend on the size of the surface area of the marking but on orientation, spacing and dimension of the marking elements. We examined achromatic marking patterns in 1,428 choice experiments with wild birds (mostly songbirds) in a flight tunnel of seven meters length. A mist net ensured that the birds suffered no injury. Twelve markings were tested; of these, eleven effectively reduced collisions. However, considerable differences existed among the tested patterns. Covering less than 7%, 2 mm wide stripes were as effective as 13 mm wide stripes covering 50% of the glass surface. Vertical stripes 10 cm apart were significantly more effective than the same pattern in horizontal orientation. To create bird protection markings on glass, designers should consider both perceptional limits and pattern related behavioural responses of birds. © 2015 Institute of Zoology, Slovak Academy of Sciences.
Fess B.,Durrell Wildlife Conservation Trust |
Glyn Young H.,Durrell Wildlife Conservation Trust |
Young R.P.,Durrell Wildlife Conservation Trust |
Young R.P.,University of Bath |
And 4 more authors.
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2010
Habitat destruction and prédation by invasive alien species has led to the disappearance of several island populations of Darwin's finches but to date none of the 13 recognized species have gone extinct. However, driven by rapid economic growth in the Galápagos, the effects of introduced species have accelerated and severely threatened these iconic birds. The critically endangered mangrove finch (Camarhynchus heliobates) is now confined to three small mangroves on Isabela Island. During 2006-2009, we assessed its population status and monitored nesting success, both before and after rat poisoning. Population size was estimated at around only 100 birds for the two main breeding sites, with possibly 5-10 birds surviving at a third mangrove. Before rat control, 54 per cent of nests during incubation phase were predated with only 18 per cent of nests producing fledglings. Post-rat control, nest prédation during the incubation phase fell to 30 per cent with 37 per cent of nests producing fledglings. During the nestling phase, infestation by larvae of the introduced parasitic fly (Philornis downsi) caused 14 per cent additional mortality. Using population viability analysis, we simulated the probability of population persistence under various scenarios of control and showed that with effective management of these invasive species, mangrove finch populations should start to recover. ©2010 The Royal Society.
Cimadom A.,University of Vienna |
Ulloa A.,Charles Darwin Foundation |
Meidl P.,Institute for Science and Technology |
Zottl M.,University of Cambridge |
And 6 more authors.
PLoS ONE | Year: 2014
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. © 2014 Cimadom et al.