I had the opportunity to speak with UNM ornithologist Ethan Linck and his colleague Ryan Terril about how our changing climate is affecting migratory and local bird populations and what effects we may see in the future.
Global bird populations have dwindled as insect populations decrease and New Mexico saw this firsthand last year when a combination of extremely cold weather and scarce food led to a mass bird die-off. This year our state is faced with a drought that has killed piñon juniper trees. According to the U.S. Forest Service, between 2014 and 2015, approximately 350 million piñon across 1.2 million hectares in the southwest have died. These trees provide shelter for a number of ground-dwelling animals as well as several species of birds. These trees also house insects that now no longer have a habitat, meaning less food for birds and other insect eaters. Without this shelter, migratory birds have to shift their routes, and local birds will move to higher elevations to escape the heat and find shade. Doctor Linck uses the phrase “escalator extinction” to describe this process of constantly moving to higher elevations to escape the heat, saying “eventually, they run out of mountain.” Increasing agrarian land and development in low elevations is also contributing to this vertical mobility, as birds have fewer and fewer undeveloped areas to nest in.
As our monsoon season slowly arrives later and later in the year, we may see fewer migratory birds that had stopped over in New Mexico in previous years to molt their feathers, explained Terril, who has been studying the effects of erratic monsoon seasons on these populations. Terril points out that “birds have to molt,” citing a study conducted in the 1970s, in which birds were kept in captivity and deliberately underfed in order to prevent them from molting, only for the birds to molt anyway, albeit very under-feathered. The monsoons provide greenery and vegetation, which in turn provide food in the form of insects and shade from the heat. Without stable annual monsoons, however, these birds will have to search elsewhere for their molting locations, as they cannot alter molting timing. This will also affect their breeding season, because after molting these birds head further north to breed, in late summer and early fall.
With later monsoons, native birds may even have a double breeding season, termed “second spring,” during the fall, in places like southern Arizona, due to plentiful plant and insect life. Terril gave an example of birds already being affected: The Painted Bunting travels from Texas to Florida along its migratory path and in previous years would have a wet monsoon area to look forward to, but due to later and later monsoons, they have been landing instead in alfalfa fields. Traditionally, these birds would see a tropical dry forest, but without monsoons they instead become dependent on human water sources used for agriculture. Just two years ago, Mesa Chivato in Thoreau, New Mexico experienced hundreds of molting migratory birds — now they’re nearly nonexistent there.
I asked both scientists what they think the public can do to help, and what sort of policies they’d like to see from our political leaders. Linck said we need to “decarbonize yesterday” and points out we haven’t fared well by hitching our economy to backwards industries like oil and gas. He pointed out that climate solutions “are not rocket science” and that it comes down to ensuring healthy, connected habitats. Terril stated we need to embrace “full annual cycle conservation,” noting that birds pass through multiple states on their migration routes that can each have radically different climate and conservation policies; therefore the need for nationwide protections.
I ran a few policy ideas by Linck and he agreed these would be great places for the local government to start. Here they are: requiring anti-collision designs for windows, controlling the stray cat population and increasing awareness of the disproportionate bird deaths caused by domestic cats, and banning pesticides.
Ordinary folks like us can plant native plants and trees, especially fruit-bearing trees and shrubs, and participate in helping scientists track bird populations by logging sightings onto the eBird app or website, https://ebird.org/home.