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.

Bring Your Cat Indoors

Great Horned Owl
Photo: Ryk Naves (Unsplash)

We heard a different owl calling in the woods behind our home today at twilight, not the familiar sound of Barred Owls. It hooted softly, as a tiger might purr to itself, watching a herd of antelopes. It was the so-called Tiger of the Woods.

Click for hooting

Great Horned Owls visit us in the fall but are never heard here in other seasons, although a pair nests in late winter only two miles away on Jamestown Island. They are our largest and most ferocious raptors. Although birds (including other owls), small mammals, and reptiles are their normal fare, they aren’t fussy about what they eat and will tackle prey larger than themselves. Bring your cats and small dogs indoors at night if you hear muted hooting after dark.

Scavengers in my Yard

Black vultures

Deer munch on our flower borders, strip foliage to head height, and rub bark off trees with their antlers in the rutting season. We grumble yet feel sad coming across a beautiful animal that died on our property after a road accident. We often find only their bones.

I rarely need to bury a carcass because scavengers soon arrive to devour all the soft tissues. Sometimes, we have more than a dozen Black Vultures crowding over it. It’s not a pretty sight and the stench of the birds can drive you back far more than the corpse. I can walk within a few feet without disturbing them because they have little fear of humans, being protected under the Migratory Birds Act. And why should I scare them away when they provide a free service?

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