Humans Boom while Birds Crash

Starling murmuration
European Starling murmuration (James Wainscoat: Unsplash)

The United Nations estimates that our population reached 8 billion this week. In 1900, it was 1.6 billion but by the turn of the 21st century, we had grown to over 6 billion. That is nearly 2 billion more mouths than only 22 years ago and the graph is still rising. Meanwhile, most wildlife populations across the globe are plunging. There’s a connection and it’s called the Sixth Great Extinction.

It is harder to estimate populations of birds than terrestrial animals, but North America alone is reckoned to have 3 billion fewer birds than 50 years ago. Seventy species out of a total of over 500 are thought to be close to a tipping point, meaning the threshold for sustaining their presence.

The Cornell Lab for Ornithology released a tool this month that maps trends in the abundance of birds from 2007 to the present. The data were provided by citizen scientists through eBird and mapped in 27×27 km squares (roughly the area of a small county). Birders and gardeners have noticed fewer birds in their localities, especially “common” birds, and this impression now has numbers. Typing the name of any species prompts the map of North America to show the trend in blue boxes for an increase, red for a decrease, and white where it can’t yet be determined with confidence.

I tested the tool for the mid-Atlantic region where I live. The good news is that geese and swans have increased spectacularly, and waterbirds and ducks are doing well too. The protected status of wetlands where there is less pollution and human disturbance is probably responsible.

There are reassuring trends for some raptors (eagles, owls, and the Red-shouldered Hawk) as well as for vultures and ravens. The Pileated Woodpecker, Carolina Wren, Wild Turkey, and Ruby-throated Hummingbird hold up well too.

But the news overall is bleak. Insectivorous species are down from a loss of habitat and prey, a large group that includes warblers and swallows. American Robins and Gray Catbirds are declining, but whatever is responsible hasn’t affected Northern Cardinals that have overlapping habitats. Hearing American Crows every day, I am surprised they are in decline, and will likely appreciate them more if they become rare!  

We can do little about the rising human population, but every landowner can help to mitigate the decline in birds by making their property a friendly habitat. This should be easier because few birds are regarded as pests. Many are beautiful and some provide services we appreciate. Farmers can leave field margins fallow for foodplants and insects to thrive. Roadside verges and hedges should be mowed and pruned after the breeding season and boring roundabouts planted with wildflower seeds. Gardeners can set aside corners of their yard for nature to creatively flourish, often as beautiful as a tidy flower bed. Our individual efforts seem paltry against the scale of the problem, but taken together they amount to an area much larger than nature preserves.

If I am around in another 15 years, I am confident of seeing more blue boxes than red on the eBird map if we manage the land differently.

By Roger Gosden

British-born scientist specializing in reproduction & embryology. Career as professor & research director spanned from Cambridge to Cornell's Weill Medical College in NYC. Married to Lucinda Veeck Gosden, embryologist for the first successful IVF team in America. Retired early to Williamsburg, Virginia, to write and recover from 'nature deficit disorder'. Currently a visiting scholar at William & Mary. https://en.wikipedia.org/wiki/Roger_Gosden

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