Always fewer window swallows, tree sparrows or skylarkers. But no more wood pigeons, oak jays or blue tits. The results of thirty years of counting birds in France, published this Monday by the National Museum of Natural History (MNHN), the League for the Protection of Birds (LPO) and the French Biodiversity Office (OFB), makes state of a “Urban and agricultural hecatomb”. And a “False good news” : the demographic progression of a few “generalist” species capable of adapting to all environments, such as the pigeon, to the detriment of “specialist” species. Which in fact reveals “A standardization of wildlife, a sign of an increasing trivialization of habitats and a loss of biodiversity”.
Generalization of insecticides
The state of health of the French avifauna is “contrast” more “Rather negative”, indicates the 1989-2019 results of the temporal monitoring of common birds (Stoc) program, which identifies the avifauna according to a protocol repeated each year by more than 2,000 volunteer ornithologists. Which is “Disturbing”, car “Birds are excellent indicators of the state of health of ecosystems”, insists the summary report. Thus, out of the 123 bird species monitored, the most common in France, the populations of “32 species are expanding, such as the white-fronted redstart or the black-capped warbler, but 43 are declining, such as the elegant goldfinch [très braconné, ndlr], the turtledove [dont la chasse est pourtant autorisée, ndlr] or the window swallow ”.
Since 1989, the Stoc has been evaluating the trends of bird communities specializing in agricultural, built and forest environments, as well as those of generalists. The most important fall concerns birds specializing in agricultural environments (such as skylarks and gray partridges), which have lost 29.5% of their numbers in thirty years. The meadowsweet, the emblem of the Stoc, a migratory species whose white eyebrow and orange chest make it a particularly elegant bird, is one of the species which has declined the most: -60% since 2001. The pipit farlouse has lost 66% of its workforce in nineteen years.
This drastic decrease in the populations of field birds “Is concomitant with the intensification of agricultural practices in recent decades, more particularly since 2008-2009, alert the report. A period which corresponds, among other things, to the generalization of neonicotinoids, very persistent neurotoxic insecticides». Another major factor in the decline of birds specializing in agricultural environments, “The disappearance of habitats which are favorable to them by the standardization of landscapes (large plots in monoculture, disappearance of hedges) in areas of intensive agriculture”.
Renovation of facades
The situation is almost as dramatic for birds that breed mainly in towns and villages, such as the swallow, the black swift or the black redstart: they suffer a decline of 27.6% in thirty years. Some are doing well, like the jackdaw or the white-fronted redstart. But many others are doing badly, such as the European greenfinch, the swift or the tree sparrow – the latter has lost 60% of its numbers since 2001. The reasons for this decline are “Still poorly explained and certainly multiple”, admits the report. Among the hypotheses mentioned are the transformation of buildings and the renovation of facades, which destroy the cavities in which certain species nest, the ever increasing artificialization of urban environments and the intensification of agriculture near urbanized areas which reduce the number of species. food resources, especially insects and seeds in winter, or pollution from transport and industrial activities.
For their part, after a sharp decline in the 90s, birds specializing in the forest environment are relatively spared. Since 1989, they have lost “only” 10% of their workforce. Even if it depends on the species: black woodpecker or core-busting grosbeak are expanding, while others are seeing their numbers decrease, such as the squid or the peony bullfinch. Among the reasons for this situation, which is less unfavorable than for birds in urban or agricultural environments, the report cites “The overall progression of the forest area in France, linked to agricultural abandonment and the evolution of forest management practices, which tend to leave more dead wood or very large aging trees in the forests, elements favorable to insects and therefore to birds”.
Impact of climate change
The species that do the best are the so-called “generalists”, such as the wood pigeon, the jay of the oaks, the blue tit, the blackbird or the chaffinch. Adaptable birds, as at home in the heart of large cities as in the bocage, in the cereal plains of the Paris basin or in mountain forests. It is the only group that is expanding (+ 19% since 1989). Even if, there too, differences exist according to the species: the blackcap is increasing (+ 30% in nineteen years) while the speckle accent is in decline (-27% over the same period). The wood pigeon, which abounds in cities like Paris, has doubled its numbers since 2001. “It seems that this is linked to the development of a sedentary population, a phenomenon attributed to changes in agricultural practices (increase in maize, sunflower and rapeseed areas in particular) and certainly favored by the succession of mild winters”, estimates the report.
He notes that the impact of climate change is already noticeable. For example, bird populations have been shown to shift northward in an attempt to stay in areas where the temperature is suitable for them. Environmental policies also have an effect on bird populations, positive that one. “Areas with a high proportion of protected areas show less significant declining trends linked to global warming”, scientists note. The Stoc has indeed made it possible to demonstrate the effectiveness of nature reserves: excluding reserves, the average decline of 56 species between 2004 and 2018 is -6.6%, while within reserves, an increase of 12.5 % is observed. “Proof that the public policy of protected areas is beneficial for nature”, estimates the report.
“We have quantified the declines, identified many of their causes and highlighted effective solutions to stop them (protected areas, less intensive agricultural scenarios). We therefore do not have the right to give up. No right to drop the last augers, the last larks ”, insists Frédéric Jiguet, professor at the MNHN and deputy director of the Research Center on the Biology of Birds Populations (CRBPO). In a joint press release with the MNHN, the LPO and the OFB, Bérangère Abba, the Secretary of State in charge of Biodiversity, takes note of these results. “without appeal”. And has this formula: “We must act by targeting our actions on agricultural and urban environments.” Extensive program, not detailed here.