Among the more than 400 species of birds that can be regularly encountered in France, most can be observed in our gardens and by the sea.
Let’s start by stating that, “from a naturalistic and biological point of view, the denomination of seabird has no value”while that of garden bird is “regularly used in a scientific program, the participatory observatory “Oiseaux des Jardins””says Jérémy Dupuy, project manager “Bird surveys and atlasesto the Bird Protection League.
“We make these groupings of species to popularize”, says the specialist. Regarding garden birds, “you can observe more than a hundred species if you are near an agricultural or wetland area, and you have a well-treed garden”. Within the “Garden Birds” program, around thirty species are listed, he adds. Seabirds are more numerous, and cover about 200 to 250 species all combined. “The areas richest in birds, in terms of quantity and diversity, are often temperate zones and wetlands by the sea”justifies Jérémy Dupuy.
As their name suggests, garden birds and seabirds are not found in the same place… for the most part! “We have a procession of species more or less associated with the garden, but for which the garden is not the main habitat. Many of them are generalist species, which adapt quite well to an improvised environment”, explains Jérémy Dupuy. Among these species, we find in particular several groups of passerines, including tits, finches, greenfinches, sparrows, but also several species of sylviids, such as warblers and woodpeckers. There are also birds of prey, like the hawk or the crow.
According to Jérémy Dupuy, seabirds bring together very different species. We first come across pelagic birds, which live offshore most of the year, such as the albatross, the puffin or even the booby. Then come more coastal species, at the interface between the continental environment and the marine environment, such as the tern, the gull or the seagull. On the coast, we finally find other birds at the level of bays, estuaries and lagoons, such as the sandpiper, as well as waders (spatulas, ibises, herons…) “There are few species that would belong to these two groups of birds, but there are some: there is for example the gray wagtail, which feeds on insects in the lawns, but which is also found in more open environments with little or no vegetation, such as the sea line”adds Jérémy Dupuy.
Plumage adapted to the environment
If it is difficult to categorize birds within the denominations “garden birds” and “sea birds” as these categories overlap with different lifestyles, there is one parameter that differentiates them: the plumage. “Most of the birds subservient to the humid environment have a significant impermeability of the plumage, which allows them to be able to dive without ending up wet and dying of hypothermia”says Jérémy Dupuy.
“For this, these birds use their uropygial gland, located at the level of the rump: it secretes a substance which makes it possible to waterproof their plumage. Land birds also have this gland, but the secretion serves them mainly to clean their plumage”says Jérémy Dupuy.
Thanks to the specificity of seabirds, water molecules do not penetrate their plumage, but glide over it, as in ducks. There is only one exception to the rule: the cormorant, which must therefore regularly stop to dry off, which explains why we often see this animal with its wings spread, drying on the ground.
Seabird or garden bird: different flight strategies
“Most species of birds are good fliers, but they each adopt different strategies”says Jérémy Dupuy. “Among seabirds, some have the ability to move thanks to the displacement of air masses from the waves. This is the case of the albatross, capable of surfing the waves without flapping its wings for hours”he says.
The shore-dwelling species are highly migratory, which perform flapping flight: after having made significant reserves of fat for several days or even weeks, they fly for several days, flapping their wings at very high altitudes, until they reach their migratory stopover or wintering area. Among garden birds, the strategies also differ: while small passerines can be diurnal migrants, like tits, others are nocturnal migrants, like the robin.
Chickadees do not fly very high and move from tree to tree with leaps and bounds, while robins will store fat then take off at night, and fly for several hours over tens of kilometres.
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