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Bird Monitoring and Research: About the MAPS project in Yosemite

August 18, 2012 Posted by: BW - Mather District Volunteer Interpretive Ranger

About the MAPS project in Yosemite
Bird banding stations in Yosemite are cooperatively run by The Institute for Bird Populations and National Park Service personnel. They are part of the Monitoring Avian Productivity and Survivorship (MAPS) Program which include a continent-wide network of over 500 constant-effort mist netting stations. The Yosemite stations are some of the longest-running MAPS stations in the country! The Yosemite MAPS stations monitor the population dynamics and demography of over 25 target bird species that inhabit the parks' montane meadows during spring and summer. In addition to contributing to the larger-scale MAPS program, the Yosemite MAPS stations yield important findings and new hypotheses about landbird population dynamics in the parks. Preliminary findings that emerge from MAPS results can then be followed up with targeted research.  

The data that is collected at these banding stations can be used to determine larger patterns in bird populations and demographics. The Yosemite Monitoring Avian Productivity and Survivorship (MAPS) stations are well-suited to studying the effects of annual weather variation and climate change on birds. Some of these Yosemite specific patterns include:

  • Researchers have determined that when there is a decrease in snowpack, the productivity of many bird populations increase. This can be seen by comparing data from last year, a very heavy snowpack year, with current numbers from the very dry 2012 season. The 2012 numbers are up by more than 39%, with most of the birds having hatched this year.  
  • Another pattern that is apparent from the data is that some species of birds have become more common at higher elevations. This is likely related to the longer term shift of climate change.  
  • The most disturbing trend though, is a general decline in the populations of songbirds. This may be related to the expansion in range of the brown-headed cowbird (Molothrus ater), which is a brood parasite, laying its eggs in another species nest.  

All of these patterns help park managers decide how to best manage the natural resources at Yosemite.


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Did You Know?

Upper Yosemite Fall with spring runoff

Yosemite Falls is fed mostly by snowmelt. Peak flow usually happens in late May, but by August, Yosemite Falls is often dry. It begins flowing again a few months later, after winter snows arrive.