27 Jun It’s Baby Season! Streaked Horned Lark Nest Monitoring
In Oregon, mid-April to late-August designates the breeding season for streaked horned larks. My main duties as the lark intern on the Willamette Valley National Wildlife Refuge Complex is to search for nests and monitor their progress. Finding nests can be a long waiting game that requires patience and hours of watching birds with a spotting scope. I mainly focus on observing females since they are in charge of building and incubating nests while males only assist in feeding nestlings. Nests are mostly built right next to vegetation and require a sharp eye since they blend in pretty well with the ground. Once I lock in on a female lark it can be 30 minutes to 2 hours before she decides to pick up some nesting material and place it down in a certain spot, revealing to me where her nest is. Since I’m watching from a distance I have to pick a distinct landmark and make a bee line, hoping I end up near the nest. Once I locate it I snap a few photos and take a GPS point. Below is the progression of a streaked horned lark nest from nest building to incubation to becoming active then sadly being depredated.
The nest building stage is about 5 days followed by 3 days of egg laying to 12 days of the female incubating and lastly it takes about 9 days for nestlings to fledge. As the designated streaked horned lark baby sitter I check nests every other day throughout the week to track their progress. Unfortunately, as ground nesters these nests are easy access for predators and often have the same fate as the one above. So far many haven’t made it to the nestling stage this season. To help keep track of all the nests I use a color coded calendar to better project hatching and fledging events, which are important during monitoring to better calculate success rates. Once a month during the season I also conduct breeding pair surveys on each refuge to identify which fields larks are occupying and how many are breeding. Stay tuned for an update on how many little larks are flying around the Willamette Valley wildlife refuges!