Sounds of Springtime

Springtime in Colorado is a tricky thing to pin down because March and April are months where we can still see a lot of snow. In fact, we got quite a bit of snow this past March, including several days where work was remote because roads were either hazardous or just completely impassable.

Never the less, there are still four seasons in the Rocky Mountains and the Front Range. This past weekend seemed to usher in some familiar signs of springtime. Greenery is still sparse in the Denver area, but here and there we've seen blossoms on some of the ornamental trees planted around the city. We even saw a few trees with budding leaves, though certainly not the majority.

My girlfriend and I like to go for walks on the weekends around Crown Hill Park in Wheat Ridge and noticed a lot of red-wing blackbirds (Agelaius phoeniceus) in the tall stalks near the water. We don't seem to remember hearing them very often from previous walks we took through the winter so it's tempting to think that their arrival is a sign of spring seasonal change, but Colorado is technically within the year round range of the birds, and southern and some western populations do not migrate (1). Also, according to ornithologists at the Cornell Lab for Ornithology, males and females make their calls all year round (2). Regardless, it's a great sound and it had been some time since our ears had heard it.

A more definitive springtime sound that we heard was that of the many chorus frogs (Boreal chorus frog, Pseudacris maculata) that were in the partially submerged grassy areas and ditches around the park. Once the snow and ice have melted and created wetland habitat in flooded meadows, drainage ditches, and small temporary ponds, the males begin to call to females to come lay their eggs (3). This can start as early in March and marks the beginning of the mating season which will continue until May (3).