Act for Our Future

© David Brezinski/ Goldfinch, US Fish & Wildlife Service

Nearly half of the 700 bird species that nest in the United States and Canada migrate some distance seasonally. Roughly 250 of them are Neotropical migrants, meaning that they travel to Latin America and parts of the Caribbean for portions of the northern winter, commuting hundreds or even  thousands   of miles annually between their summer and winter habitats.

Recent  studies, however, have shown that climate change may now be affecting the timing, behavior, ranges and population dynamics of many of these migratory bird species. One concern is the synchronicity between trees, caterpillars and bird nesting activity in the spring. Many spring song birds have evolved to time their arrival and nesting to subtle climate clues. But now these cycles of trees,  caterpillars and the arrival of the birds that eat them are being thrown out of synch by climate change. Parallel climate impacts in both winter and summer ranges further increase threats to these migratory species.

Indiana in particular is an important stopover for several species on their migratory path.  Without stopover sites, these species would not be able to find the food needed to complete their journey.  The migratory bird species most commonly stopping in Indiana include the American Golden-plover, Barn Owl, Common Nighthawk, Hermit Thrush, King Rails and Lesser Yellowlegs, to name a few.

Other climate change impacts can also affect migratory birds by altering their habitats via sea level rise, changes in fire regimes and changes in vegetation or land use.

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Bandelier National Monument,
New Mexico

Bandelier is becoming drier and hotter as temperatures rise. The Colorado Plateau region which spans much of Utah, Colorado, New Mexico, and Arizona is experiencing shrinking water supplies with amplified heat. According to the National Parks in Peril report, “The Colorado River basin, which includes The Colorado Plateau, has experienced more warming since the 1970s than any other part of the United States outside of Alaska.”

These warmer, drier conditions are already impacting the region’s dominant wooded ecosystem—piñon-juniper forests.  Piñon bark beetle infestation flourished as piñon-juniper trees were weakened from sustained drought and heat earlier this decade.  Large die-offs occurred in Bandelier in 2002 and 2003. While this region has experienced drought before (drier period existed in the 1950s), the die-offs are even worse due to the additional stress of higher temperatures. In addition, opportunities for outdoor, winter activities will likely decline.

Learn more about national parks in danger

Of all migrations by small creatures, few are as astonishing as that of the Monarch butterfly. These fragile insects travel between 1,200 and 2,800 miles or more and back every year.  Like several species of birds, bats and whales, the Monarch butterfly of Canada and the United States migrates to places where the climate is less extreme. Winters are too cold in the places where the butterflies reproduce; they could not withstand either heavy snowfall or the lack of plants on which larval caterpillars feed. So each Fall, the Monarch heads south in search of warmer weather.

For Monarchs migrating south to Mexico every year, the long journey moves at a pace of almost 50 miles a day.  At the end of October and the beginning of November, after traveling two months, the butterflies settle into hibernation colonies in the mountains of central Mexico, where the States of Mexico and Michoacan meet. There they will spend the winter hibernating.

From mid-November until mid-February, the Monarchs' hibernation colonies remain relatively stable. During the second half of February, when temperatures rise and humidity decreases in the forests, the butterflies come down from the slopes to mate. Those that have survived hibernation in Mexico return in the spring to the southern United States.

Climate change threatens to disrupt this annual pattern on which the Monarch’s existence depends by affecting weather conditions in both wintering grounds and summer breeding grounds.  Colder, wetter winters could be lethal and hotter; drier summers could shift suitable habitats north.

Learn more about monarch butterflies 

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