Zwaluwen

Aerially-foraging insectivorous bird populations have been declining for several decades in North America and habitat loss is hypothesized as a leading cause for the declines. Chimney Swifts (Chaetura pelagica) are a model species to test this hypothesis because nest site use and availability is easily assessed. To determine if nest site availability is a limiting factor for Chimney Swifts, we established a volunteer-based survey to inventory and describe chimneys (n = 928) that were used or unused by swifts.

The influence of crop type (pasture, silage and cereal) on the abundance of aerial invertebrates and the density of foraging barn swallows Hirundo rustica was investigated in lowland mixed farmland in southern Britain. After taking weather and other confounding factors into account aerial invertebrate abundance over pasture fields was more than double that over silage, and more than three and a half times greater than that over cereal fields. Pasture fields also hosted approximately twice as many foraging barn swallows as both silage and cereal fields.

Data collected by the U.S. Geological Survey (USGS), as part of the Pesticide National Synthesis Project, show that use of neonicotinoids in agriculture rose from about 150 metric tons (all imidacloprid) in the late 1990s and early 2000s to between 510 and 625 tons in 2004. From 2004 to 2007, these figures nearly doubled, and in 2012, according to USGS data, between 2,677 and 2,819 tons were used. Data for 2013 and 2014 are still preliminary but suggest the numbers have continued to rise.

Vermont is famous for its natural and mesmerizing landscape that includes a big forest. Unfortunately, a recent report has revealed the decrement of the bird population there. ABC News reported a sharp decline of 14.2 percent in the bird population over the last 25 years in the Vermont forest. The latest study has unveiled this crucial fact. Several rare and common bird species exist in the said forest. Among them, some species solely depend on the flying insects and they form a major portion of the bird population.

Fewer birds appear to live in Vermont today than 25 years ago, according to recent research by the Vermont Center for Ecostudies. The most dramatic declines in bird populations were seen among those that live off flying insects, scientists say. Known as aerial insectivores, this diverse group of birds has declined 45 percent in Vermont, according to the study.

Die Fledermäuse erwachen momentan aus dem Winterschlaf. Nachts gehen sie auf die Jagd, um ihre leeren Reserven aufzutanken. Doch sie finden kaum noch Futter. „Seit einiger Zeit beobachten wir einen alarmierenden Rückgang von Insekten“, sagt Karl Kugelschafter, Fledermausexperte vom Naturschutzbund (Nabu). Für die Fledermäuse geht es ums Überleben, denn sie ernähren sich fast ausschließlich von Insekten und müssen pro Tag ungefähr ein Drittel ihres Körpergewichtes an Nahrung zu sich nehmen. Hochgerechnet braucht ein einzelnes Tier also ungefähr ein Kilogramm Insekten in einem Sommer.

With this week bringing summer-like weather across much of France, swallows have also started to arrive in numbers – but those numbers are down on previous years. Swallows and house martin populations have fallen about 40% since the first count was done in France in 1989 – with man being the main reason for their decline. A study by the Fondation 30 Millions d’Amis said swallows were 42% down and house martins (Delichon urbicum) 39% down as an already reduced population was hit by the effects of droughts when they were over-wintering in Africa.

Die Rauchschwalben sind erfahrungsgemäß die Ersten, die sich im Rhein-Main-Gebiete zeigen: Ende März, Anfang April sind die Schnellsten zurück aus den Winterquartieren. Bis in den Mai hinein dauert es, dann sind alle Tiere der verschiedenen Schwalbenarten hier, um zu brüten. Genau beäugt werden sie dabei von Helfern des NABU, denn die Vögel sind gefährdet. Der Bestand in Deutschland hat sich in den vergangenen Jahren drastisch verschlechtert: In der aktuellen Roten Liste der Brutvögel wurden die Mehl- und Rauchschwalben von der Vorwarnliste in die Kategorie 3 („Gefährdet“) heraufgestuft.

In weiten Teilen Deutschlands ist die Insektenpopulation um bis zu 80 Prozent eingebrochen. Vor allem Wildbienen, Hummeln, Schwedfliegen sowie den Tag- und Nachtfaltern drohe das schleichende Aus, mahnt Thomas Mitschke. „Allein die Rote Liste der Bienen umfasst 300 Arten.“ Der Vorsitzende des Naturschutzbundes Lüneburg ist Hummel-, Wespen- und Hornissenbeauftragter für Stadt und Landkreis Lüneburg.

Unfortunately the common nighthawk (Chordeiles minor) isn’t all that common anymore. From May until September, Canada hosts an estimated 900,000 of them, coming here to nest before their long trip to South America where they wait out the winter. But we used to harbour considerably more back in the day. From 1973 through 2012 it’s been estimated their population plummeted some 76 per cent, and by no means has that trend slowed down. Those 900,000, estimated as such in 2013, are merely the survivors of a nation-wide decline.