Many common species are in decline

Keith Barnes/Tropical Birding Raptors in Botswana (such as this Bateleur) are fairing poorly outside protected areas Zoom In

In many parts of the world, familiar bird species that we value are in decline. This shows that we are not managing our environment sustainably.

Bird declines warn us of wider environmental problems

Birds have long been used to provide early warning of environmental problems. The decline of bird populations in many parts of the world is of considerable concern, indicating a fundamental flaw in the way that we treat our environment.

Declines of common species in temperate regions indicate unsustainable land use

Population trends of common and widespread bird species can serve as useful indicators of sustainable development, and in Europe and North America they are increasingly being used to support otherwise qualitative claims of biodiversity loss. A recent initiative to generate the first pan-European indicators for common wildlife populations — combining data from a number of high-quality national monitoring schemes — delivers an alarming message about the state of Europe’s common farmland birds (see pdf case study, box 1). The North American Breeding Bird Survey (BBS), meanwhile, has been running for almost 40 years, monitoring population trends of more than 400 of the continent’s bird species. Analysis of BBS data from the agricultural landscapes of eastern and central USA implicates changes in agricultural land use in the continuing declines of the region’s open-country birds (box 2).

Birds are also declining in the tropics and sub-tropics

Across much of the tropics and subtropics — the home of most of the world’s species — it is often necessary to estimate population trends using indirect information, such as national distribution atlases and species-mapping schemes (box 3). Combined with the interpretation of site-based census data and land-use changes (box 4), these provide strong evidence that many common tropical and subtropical bird species are also declining.

Boxes: case studies and scientific analyses

Download SOWB pp.8–9 (PDF, 377 KB) containing the following:

1. Europe-wide monitoring schemes highlight declines in widespread farmland birds
Common bird index (1965-2000), c.40 species in c.18 European countries

2. Grassland birds are declining in North America
Red-winged Blackbird populations declining in USA

3. Common birds are disappearing in eastern Australia
Comparison of two atlas studies

4. Raptors in Botswana are faring poorly outside protected areas
Woodland raptor declines, Botswana