To monitor climate change, scientists and novices are recording differences in the migrating behavior of birds as they adapt to changing conditions.
A National Wildlife Federation report earlier this year found that migratory birds are particularly threatened because they depend on multiple habitats.
Migratory birds depend on certain triggers — often changes in daylight or weather, depending on the species — to know when to migrate, and count on food sources being available to them when they arrive in their destination. In some places, springs are starting earlier — last year's spring was the earliest ever recorded in the U.S. — and in others, they're starting later than ever. They're also starting and stopping, with warm weather followed by bitter cold, which can damage new growth on trees and plants and kill off insects that have already hatched. Many of the insects and flowers that birds eat in the spring hatch and bloom when the weather gets warm, so an early or false spring in one part of the world could mean birds arrive in an area with nothing to eat, which could ultimately harm bird populations.
The red knot, a shore bird on the Atlantic and Pacific Coasts, is a good example, says Doug Inkley, the National Wildlife Federation's senior scientist.
"Some migrate as far as 9,300 miles from their Arctic breeding grounds to the southernmost tip of South America where they overwinter," he said. "But in Delaware Bay, where virtually the entire Atlantic red knot population goes to fatten up on horseshoe crab eggs for the energy they need to finish their arduous journey back to their Arctic breeding habitats, there are signs climate change is throwing off that critical timing between red knot arrival and horseshoe crab egg laying. That's what we're worried about here. Break just one link of the chain and the entire species is in grave danger."
But some birds are proving their ability to quickly adapt to changing conditions. A study conducted by scientists from the University of Oxford looked at a population of great tit birds living near the school.
From Science Daily:
By studying individual birds over multiple years, the team were able to show that individual birds have a built-in flexibility that enables them to adjust their behaviour rapidly in response to short-term changes in the environment. This flexibility — known as phenotypic plasticity — greatly increases the chances that a population can survive in spite of short-term changes, but that possibility depends on how closely they can track the key aspects of their environment, such as the availability of food. As species become longer-lived, and thus slower to reproduce, evolutionary adaptation is far slower and can't on its own save such species from climate change-induced extinction.
LEARN MORE ABOUT BIRDS AND CLIMATE CHANGE:
• Meet Bob Janssen — the bird man of Minnesota
When completed, Janssen's bird survey will be used for scientific purposes, too. The data he collects for the state DNR will be combined with his 60-plus years of research to determine whether or not there's a relationship between global warming and changes in bird nesting and migration patterns. (Star Tribune)
• Biologists worried by starving migratory birds, seen as tied to climate change
At the Maine Coastal Islands National Wildlife Refuge, the tiny bodies of Arctic tern chicks have piled up. Over the past few years, biologists have counted thousands that starved to death because the herring their parents feed them have vanished. (Washington Post)
• Birds and Climate Change: On the Move
Nearly 60% of the 305 species found in North America in winter are on the move, shifting their ranges northward by an average of 35 miles. Audubon scientists analyzed 40 years of citizen-science Christmas Bird Count data — and their findings provide new and powerful evidence that global warming is having a serious impact on natural systems. (Audubon)