Zwaluwen

Viele Arten kämpfen ums Überleben

Der 22. Mai war der Internationale Tag der biologischen Vielfalt – doch nach wie vor verschwinden viele Arten. Das von der Europäischen Union gesetzte Ziel, diese Entwicklung bis spätestens 2020 zu stoppen, wurde bislang nicht erreicht: „Es ist eher davon auszugehen, dass wir viele weitere Arten, Lebensräume und genetische Vielfalt bis zum Ende dieser Dekade verlieren werden“, sagt Gernot Segelbacher, Professor für Wildtierökologie und Wildtiermanagement der Fakultät für Umwelt und Natürliche Ressourcen an der Albert-Ludwigs-Universität Freiburg.

North American Bank Swallow numbers declined by 94% from 1966 to 2014

Swallows are small, speedy, short-winged aerial hunters with slender bodies and pointed wings and a tail, just like a jet airplane. The birds are quick and graceful in flight, often catching a variety of flying insects in midair during a long, dizzying air travel pattern near the water or in a meadow. These short-billed aerial hunters know exactly what they are doing. A single Barn swallow (Hirundo rustica) , for example, can consume 60 insects per hour, an amazing 850 per day. The small birds are surely one of Mother Nature’s most successful avian insect predators.

Noch weniger Vögel in der Agrarlandschaft von Mecklenburg-Vorpommern

In Mecklenburg-Vorpommerns offener Landschaft gibt es immer weniger Vögel. Darauf hat der Naturschutzbund Deutschland (Nabu) nach der diesjährigen Zählaktion „Stunde der Gartenvögel“ hingewiesen. „Während sich bei den Vögeln unserer Dörfer und Städte über die Jahre Zu- und Abnahmen die Waage halten, gibt es auf den Wiesen und Feldern fast nur Verlierer“, sagte der Nabu-Landesvorsitzende Stefan Schwill am Donnerstag in Schwerin.

Stille ramp: de insecten verdwijnen

Er zijn steeds minder insecten. Uit onderzoek blijkt dat de hoeveelheid insecten in de natuurgebieden rond het Duitse Krefeld met bijna 80% is afgenomen in 25 jaar van 1989 tot 2014. Een afname die volgens een publicatie in Science niet alleen in Duitsland geconstateerd wordt, maar ook in andere landen. Zo daalde het aantal insecten in Schotland met 60%. Het onderzoek in Krefeld werd uitgevoerd in natuurgebieden waar niet zo extreem veel was veranderd in het beheer van die gebieden zelf. Maar in de omgeving is wel veel veranderd.

No Sign of Swifts in May's Britain

Normally my first sighting of swifts – the dark, scythe-winged birds that scream over our summer rooftops – is on voting day in May. I can’t blame them this year. If I’d spent the past few months swooping over the Congo and Mozambique, I’d have shunned the cold grey mizzle that greeted voters yesterday. Swifts (Apus apus) are among the last summer visitors to arrive and the first to leave, flying south as soon as they have raised their young. They were made for flying and only touch down to nest.

Bird populations in steep decline in North America

North America has more than a billion fewer birds than it did 40 years ago, with the snowy owl (Bubo scandiacus) and the chimney swift (Chaetura pelagica) just two of the better-known species in dramatic decline across the continent, a recent survey has found. The total number of continental landbirds stands at about 10 billion, down from about 11.5 billion in 1970.

Neonicotinoid insecticides can persist in water for a long time and are disrupting the food chain for wildlife

Studies on the risks of neonicotinoids have often focused on bees — pollinators vital to farm production that have been experiencing population declines — but “it’s really not just about bees,” said Christy Morrissey, a professor in the Department of Biology at the University of Saskatchewan.

Where have all the insects gone?

Entomologists call it the windshield phenomenon. "If you talk to people, they have a gut feeling. They remember how insects used to smash on your windscreen," says Wolfgang Wägele, director of the Leibniz Institute for Animal Biodiversity in Bonn, Germany. Today, drivers spend less time scraping and scrubbing. "I'm a very data-driven person," says Scott Black, executive director of the Xerces Society for Invertebrate Conservation in Portland, Oregon. "But it is a visceral reaction when you realize you don't see that mess anymore."

Loss of nesting sites is not a primary factor limiting Chimney Swift populations

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.

Effects of crop type and aerial invertebrate abundance on foraging barn swallows

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.