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Phenology and Climate Change


Phenology is the timing of biological events throughout the year, such as leaf out in the spring, emergence from hibernation, the arrival of migrating birds, and the appearance of adult insects. Many species of migratory birds have shifted their arrival dates as much as 3 weeks earlier over the last several decades. Such migration shifts have the potential to cause birds and other species to no longer be in synch with available food supplies; conversely, the foods may be ready earlier than the animals that depend on them are feeding. This breakdown in timing may cause a mismatch in what wildlife species need in their habitat versus what is available at very critical times for their survival.



How Changing Phenology Affects Wildlife


A large number of unpredictable changes involving phenology are the result of climate change. Not all interdependent species will shift at the same rate—if they shift at all—and the resulting mismatches have the potential to disrupt reproduction, predator/prey cycles, and pollination as examples. Some birds have evolved to time their migrations to coincide with the emergence of insects. If insect emergence is too early because it is warmer, birds may miss their opportunity to feed in early spring, a time when they really need to recover from their migration and prepare for breeding.


Another example of a mismatch is the declining moose population and the winter tick. In the last three decades, winter weather in New Hampshire has decreased by three weeks. This change results in more favorable conditions for winter tick survival. When the ticks fall off the moose in the spring they are less likely to fall on snow and die. The timing of the ticks dropping and the arrival of spring has changed, the phenology is different. The ticks not only cause increased death in new moose calves but they also cause a reduction in the ability of cows to bare calves due to poor health.


What Fish and Game Is Doing in Response to Changing Phenology


Fish and Game biologists are assessing phenological changes that impact species in New Hampshire with a focus on those that rely on specific phenology for important life stages where climate change is likely to shift the timing of some of these biological events. A good example is the work to expand pollinator (such as bees, wasps, butterflies and moths) habitat in New Hampshire. The monarch butterfly, for example, migrates to Mexico in the fall and needs to have a sufficient milkweed crop for food before it departs. Pollinators are essential for pollinating important food crops like apples, blueberries and corn.


Phenology Changes and People


Wildlife improves our quality of life and provides a huge contribution to New Hampshire’s economy. The 2011 US Fish and Wildlife Service National Survey of Fishing, Hunting and Wildlife Watching shows that $554,000,000 was spent on wildlife-related recreation in New Hampshire. The hundreds of species of wildlife that depend on the many habitats in the state are important to wildlife watchers, anglers, hunters, and all outdoor enthusiasts. One example of an effect of phenology is earlier and erratic sap production by maple trees, which is beginning to affect the maple syrup industry and related tourism.


Taking Action

  • Check out A.T. Seasons, which is a citizen science season-tracking effort on the Appalachian Trail from Georgia to Maine.
  • Educate yourself and share your understanding with friends and family about how climate change affects wildlife and habitats.   
  • Start planning now for good ecological health and get involved in your local community by addressing potential climate change issues in your town or region.   
  • Support and volunteer for environmental and conservation organizations that address climate change impacts to wildlife and habitats.
  • Become a citizen scientist and help collect data on plants, wildlife, water, and weather.
  • Here are some phenology citizen science programs: