With the exception of domesticated birds, there will actually be only four species More than a billion people(The bird, not surprisingly, is in the leadership position)Passerby), Followed by Starling sansonnet (Sturnus vulgaris) , Nawras (Laros delawarensisBased on Barn swallow (Country swallow). But on the back of the pack, there are at least 1,180 species (out of nearly 10,000) that have fewer than 5,000 reps each.
This is The first full estimate of this kind in 24 yearsAnd the former was between 200 and 400 billion non-domestic birds. The number may have been overestimated at the time: researchers They say that they recline today More advanced methods for reaching more accurate totals. But the gap is still large enough to question which part is due to the decline in bird numbers in recent decades.
Their accounts are partly based on data provided by citizens in the database. eBirdAnd partly on extensive studies conducted on more than 700 species. This is the intersection of the data Who attends Greater reliability of their model, Write researchers In the review PNAS. But there are also weaknesses: There are more bird watchers in the north than in the south, at least those who have the time to report their observations in a database. The value of extrapolation also becomes uncertain for species on which we have very few observations.
But although imperfect, it is the kind of mathematics that biologists and ecologists interested in preserving an ecosystem need. In addition to the fact that this form of cross-referencing data between “hobbyists” and “specialists” can provide ideas for making censuses of other species.
Photo: UFSWS / Pixnio
