Birds are in the news spotlight this week.  A report published in the Proceeding of the National Academy of Sciences describes the first comprehensive effort to accurately estimate the total number of birds for approximately 9,700 different species or 92% of all species known to exist.  Collectively, there are roughly 50 billion individual birds in the world.  

To determine the relative abundance of each species, researchers from the University of New South Wales used citizen science data from sightings recorded in eBIrd.  The data was aggregated from January 2010 through May 2019.  Range maps were used to adjust population areas.  From there, some careful mathematical modeling based on multiple factors informed how the team calculated the bird population density. 

Four bird species — only four — each has populations that exceed one billion members.  These include House Sparrows (Passer domesticus), European Starlings (Sturnus vulgaris), Ring-billed Gulls (Larus delawarensis), and Barn Swallows (Hirundo rustica).  The top 10 species account for just shy of 10 billion birds.  This means that 0.1% of bird species account for 20% of the entire bird population.  Conversely, 12% of all species have fewer than 5,000 individual birds.

The research team believes that beyond the value of knowing how many birds there are by type, perhaps more importantly, their methodology can be used to estimate the quantity of almost any other organism in the world.  This will be a powerful new tool for environmental and conservation strategy and management. 

To read more about the methodology of this study, see this PNAS paper here:



One of the birds that was counted was certainly the Griffon Vulture (Gyps fulvus).  About 50 years ago, this large bird of prey, became extinct in Bulgaria.  But a restoration effort begun in 2009 has successfully reintroduced breeding pairs into the Eastern Balkan Mountains.  

From the beginning of the program, a total of 135 Griffon Vultures that were recovering or captive-bred in zoos and rehab centers were released.  As of December 2020, breeding pairs have produced more than 30 wild-born chicks that have fledged.

The reintroduction effort has been declared a success, despite a 33% mortality of those released.  The vultures still need support, including supplemental feeding. Despite the challenges, the birds are making these mountains theirs again.

You can read more about the reintroduction here:


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