The 10-year migration count trends for the Northern Harrier across North America shows 47.5% of sites recorded stable counts, 30% recorded decreases and 22.5% of sites showed increasing trends. The decreasing counts were present in every region. The 20-year count trends suggest more stable numbers. Regional patterns show clusters of declining counts in West and East (see map).

Winter survey data from the Christmas Bird Count (CBC) show mostly stable 10-year trends continent-wide from 2009-2022. However, declines are noted in numbers wintering in southern states surrounding the Gulf as well as Quebec and other parts of Canada. A similar trend is seen in long-term eBird abundance data from 2012-2022. These data report a decline of 23.8% for the Northern Harrier across its range, with the sharpest declines in population abundance seen in Canada (28% decline).

The Northern Harrier is listed as Threatened or Endangered in New England and is Threatened in Pennsylvania and some eastern states. It is a Species of Conservation Concern in Oregon, the Great Plains, the Southwest, and the Intermountain West, primarily due to loss of grassland habitat. It is listed as a Species of Least Concern by the IUCN Red List. More research is needed to understand the observed declines in migration counts throughout this species’ range. Habitat loss, climate change, and an increase in diseases such as West Nile virus may all be shaping the trends in this species.