Seasons of Wildlife

Kenai Nature Trail Observation Deck

The climate of the Bitterroot Valley is characterized by cool summers, generally light precipitation, little wind, and relatively mild winters. Annual precipitation averages about 13 inches but is variable related to position in the valley. The growing season in the Valley averages about 103 days; on average, the last freeze occurs May 30, and the first frost occurs September 10.

  • Spring

    Wildlife Viewing Area in Spring

    Spring is the wettest season of the year; about 25 percent of the annual precipitation occurs during May and June. Runoff via the Bitterroot River drainage is highest in spring; 55 percent of the river’s discharge also occurs in May and June following snowmelt and local rainfall. Most years there is regular backwater flooding; in periodic years there is overbank flooding that inundates large areas of the floodplain for brief periods of time. These drainage forces, the Bitterroot River most obvious, created the heterogeneous mix of communities: riverfront and gallery forest next to the Bitterroot River and floodplain drainages, persistent emergent wetland communities along floodplain drainages and fluvial-created depressions, wet meadow habitats, and grassland and sagebrush communities on higher elevation terraces and alluvial fans. 


    For you wildlife watchers, each community does not have strict boundaries, but different species favor some over others...adjust your efforts accordingly. Eighty-nine percent of the birds on the Refuge checklist can be found during this season; riparian species of interest is Lewis's woodpecker. The blooming period for the 400+ plant species on the Refuge overlaps with the summer season; an early season beauty is sagebrush buttercup. Numerous butterfly species can also be found when flowers, muddy puddles are available with sunny skies and at temperatures above 60 degrees. Red squirrel and yellow-pine chipmunk are readily found in the Wildlife Viewing Area. Basking turtles (painted turtle) on woody debris of Pond 5 are favorites for many local visitors.

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  • Summer

    Pond 10 Photography Blind

    Little rain falls in the summer, though thunderstorms can occur. Typical feature of these storms are "dry lightning" strikes, the cause of wildfire activity on extensive National Forest lands off the Bitterroot Valley floor. Natural flows in the Bitterroot River decline from spring peaks throughout the summer and remain relatively stable through winter. 


    Blooming for many plant species is still ongoing no matter the community type. Bird activity for songbirds (song and foraging) will be good early in the morning and rapidly decline after 10 am. Shorebirds are different and migrate through (both to and from their breeding grounds) during this season; they can found on Refuge wetlands given extensive areas of shallow water depths. Butterfly activity continues; some species flight season will end, other species flight season will begin. Dragonfly abundance peaks, close to 30 species can be found depending habitat type, time of day, and specific flight period. 

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  • Fall

    Wildlife Viewing Area Trail in Spring

    Fall is a time of plenty for most wildlife, for good reason as fat is necessary for migration and/or surviving winter conditions. First frost typically falls near the date of September 10. Diurnal temperature variation averages above 30 °F (17 °C) from late June thru late September (Wikipedia). 


    Fall colors of black cottonwood and western larch can be prolonged and spectacular given favorable climatic conditions.

    Fall migration of birds on the Refuge is not marked by large, definitive waves, more so by a steady presence of resident species with a low volume mix of migrants. A careful and deliberate (frequent stops listening for call notes) walk at the Wildlife Viewing Area is a good tactic for finding the feeding flock, ergo passerine migrants. No need to start at the crack of dawn, however you definitely do not want to be looking intensely during times of 90+ degrees. Migration can start as early as the first week in July for shorebirds and continue into September. Make sure you cover all the available habitats (Kenai Nature Trail for grassland/wetland) to maximize your chances of finding targeted species.

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  • Winter

    Pond 6 in Winter

    The Refuge participates annually in the Stevensville Christmas Bird Count and has listed over 55 species for the count over the last several years; the key group found are birds associated with water. Looking for and identifying mammal tracks in the snow can also be productive and fun. Don't forget to look for colorful plants that do not flower in a traditional sense or season of the year, i.e. lichens. Winter wildlife watching is of course more difficult, but offers different opportunities given climate realities.

    Wikipedia has summary winter climate data for Missoula as follows: a) the monthly daily average temperature for December is 23.9 °F (−4.5 °C) b) there is an average of 45 days where the temperature does not rise above freezing, and 7.8 days with sub-0 °F (−18 °C) lows annually. December and January have the least amount of sunshine compared to the other months.

    Natural flows in the Bitterroot River decline from spring peaks throughout the summer and remain relatively stable through winter. Climate data for Montana show a slight reduction in annual precipitation and increases in temperatures over the last 100 years (National Climatic Data Center 2011). Climate change impacts predicted in the Rocky Mountains are rising temperatures, less snow, less water in snowpacks, earlier spring snowmelts, and lower streamflows in the summer.


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