Bosvogels

Ground-foraging insectivores are prominent among the 26 species considered ‘declining woodland birds’ in southern Australia but the mechanisms driving their declines remain elusive. We synthesised existing dietary records of a subset of the 26 declining woodland birds – 13 ground-foraging insectivorous passerines – to determine the range of arthropods consumed and to estimate the relative importance of each prey group for these birds. Declining insectivores consumed a wide array of arthropods, but diets were characteristically dominated by one or two prey groups: Coleoptera, Formicidae and Lepidoptera accounted for 58% of prey records. Coleoptera contributed the greatest proportion of records (27%) and was the dominant prey group in the diets of nine of the 13 birds. These popular prey groups likely represent core resources supporting populations of declining insectivores and measurement of their abundance may provide meaningful estimates of the availability of prey.

The breeding success of Lesser Spotted Woodpeckers Dendrocopos minor is now lower in England than found in studies elsewhere in Europe. Nests were monitored in three regions of England, recording survival and causes of failure. We measured aspects of food limitation and parental care, rainfall and Great Spotted Woodpecker interactions at nests, to explore whether there was any evidence that these factors were related to breeding success. We compared results to other studies from the UK and continental Europe. Nest survival was 52%. The average number of chicks produced from successful nests was 2.8. Chick-stage daily nest survival was positively related to provisioning rates, indicating that food supply may be limiting. The most common cause of nest failure was presumed starvation of chicks after the disappearance of an adult. Some females ceased visiting nests, leaving provisioning solely to the male. This behaviour has been reported elsewhere in Europe, but in the present study males were unable to compensate fully by increasing their provisioning rates, leading to poor nest survival. Provisioning rates and chick-stage daily nest survival were negatively associated with rainfall. Nest predation by Great Spotted Woodpeckers occurred but was a less frequent cause of failure. Aggressive interactions were recorded between the two woodpecker species but these were unrelated to breeding parameters. Low breeding success is most probably related to food shortages in the breeding period. Simple population modelling using parameters from the present study and from published work shows that if the low productivity that we have observed is replicated throughout Britain, it would be sufficient to account for the observed population decline.

Imidacloprid is a systemic insecticide effective in controlling the exotic pest Adelges tsugae (hemlock woolly adelgid) in eastern hemlock (Tsuga canadensis) trees. Concerns over imidacloprid impacts on nontarget species have limited its application in southern Appalachian ecosystems. We quantified the movement and adsorption of imidacloprid in forest soils after soil injection in two sites at Coweeta Hydrologic Laboratory in western North Carolina. Soils differed in profile depth, total carbon and nitrogen content, and effective cation exchange capacity. We injected imidacloprid 5 cm into mineral soil, 1.5 m from infested trees, using a Kioritz soil injector. We tracked the horizontal and vertical movement of imidacloprid by collecting soil solution and soil samples at 1 m, 2 m, and at the drip line from each tree periodically for 1 yr. Soil solution was collected 20 cm below the surface and just above the saprolite, and acetonitrile-extractable imidacloprid was determined through the profile. Soil solution and extractable imidacloprid concentrations were determined by high-performance liquid chromatography. Soil solution and extractable imidacloprid concentrations were greater in the site with greater soil organic matter. Imidacloprid moved vertically and horizontally in both sites; concentrations generally declined downward in the soil profile, but preferential flow paths allowed rapid vertical movement. Horizontal movement was limited, and imidacloprid did not move to the tree drip line. We found a negative relationship between adsorbed imidacloprid concentrations and soil microarthropod populations largely in the low-organic-matter site; however, population counts were similar to other studies at Coweeta.

When I was a wee lad, flocks of these noisy yellow finches routinely filled my yard. Through the ’80s and early ’90s, they cost me a fortune in sunflower seeds. Even though they were avian vacuum cleaners at my feeder, I cherished them for their gregarious cheerfulness. Originally, this was a western bird. It was abundant in the Columbia River Basin in the 1830s, where it was originally studied by early scientists. The first record of a Maine sighting was in 1890. Until the 1900s, it was not known to be nesting anywhere east of the Great Lakes. In 1926, the first confirmed breeder in New England was discovered in Vermont. The next nesting pair in Vermont wasn’t noted until 1953. Soon thereafter, it was an abundant feeder bird across northern New England, with populations peaking in the early 1970s. It’s been downhill ever since. The evening grosbeak (Coccothraustes vespertinus) uses its big bill to open big seeds. It’s strong enough to crack a cherry pit. However, growing babies need protein, so nestlings are routinely fed grubs and larvae. One theory for the decline is that the population rose and fell with the spruce budworm. There are several other northern forest species whose numbers also increased when the budworm and its larvae furnished abundant food.

Eine der am meisten bedrohten Vogelarten Deutschlands, der Schreiadler, befindet sich weiterhin in einem kritischen Zustand. Der Bestand des „Pommernadlers“ Aquila pomarina ist in Mecklenburg-Vorpommern von 95 Brutpaaren Mitte der 1990er Jahre auf 80 Brutpaare (Stand 2010) weiter gesunken. Als Hauptursachen der Gefährdung machen Experten den Rückgang von extensiv bewirtschaftetem Grünland und die hohe Nutzungsintensität in unseren Wäldern aus. Schreiadler sind sehr störungsempfindliche Vögel, die von Menschen weitgehend ungenutzte Lebensräume benötigen. Ihren Verbreitungsschwerpunkt besitzen sind in Zentral- und Ost-/Südosteuropa. Die Bestände in Nordostdeutschland stellen das westlichste Vorkommen der Art dar. Hier leben sie vor allem in laubholzreichen Wäldern, die von extensiv genutztem Grünland, Feuchtgebieten und Mooren umgeben werden. Zur Nahrung des auch gern zu Fuß jagenden Adlers gehören Frösche, Mäuse, Eidechsen und andere Vögel.

An iconic but little-known Adirondack bird is dipping toward extinction in the state and likely can only be saved by bringing birds from Canada or other states to strengthen breeding. That is the conclusion of a new study on spruce grouse (Falcipennis canadensis), a bird common in Canada but much less so in New York and the Northeast. After decades of decline, there are now just 100 or fewer specimens in three Adirondack counties. At the turn of the century, the bird occupied as many as seven Adirondack counties. As recently as the 1970s, there were an estimated 300 birds, but numbers have steadily dwindled. The bird is now on the state endangered species list."We need to do something real soon, in the next few years," said John Ozard, head of wildlife diversity for the state Department of Environmental Conservation. Otherwise, odds now are 1-in-3 that spruce grouse will disappear from the Adirondacks by 2020, according to a DEC study released Friday.