If you’ve ever walked past an open grassy field in late spring and heard a chaotic, joyful burst of birdsong that sounds oddly mechanical in nature, you’ve likely just met a Bobolink. Sporting a creamy yellow nape, black underparts, and vividly patterned white and black upperparts, the male Bobolink is hard to miss. Bobolinks exhibit striking sexual dimorphism, with the female plumage consisting of warm buffy-yellow tones and dark brown streaking on the back and flanks. One may confuse a female Bobolink for a large sparrow, but the experienced birder will distinguish her by her larger size and brighter, more yellow-brown hues. Beyond their unique plumage, these birds are incredible long-distance migrants, traveling thousands of kilometres to overwinter in the grasslands of South America.

 

Due to substantial population declines driven by habitat loss, the Bobolink is federally listed as Threatened under the Species at Risk Act and is red-listed in British Columbia, where it almost entirely dependent on agricultural areas for breeding sites. Bobolinks can be found at many locations within the Creston Valley, and a small breeding population is present south of Duck Lake within the CVWMA. CVWMA staff have been monitoring this population since 2022 through a series of field surveys throughout each breeding season. Through these ongoing efforts, we are working to answer a few key questions:

With these goals in mind, our team heads to the field during the peak of the breeding season from late May through early August. By walking standardized transect lines and mapping birds’ behaviours such as adults carrying food or nesting materials, or alarm calling, we can confirm nesting activity without physically locating nest sites. Bobolinks build ground-level nests concealed at the base of tall, dense vegetation – they are extremely tricky to find! Male Bobolinks are aggressive and strongly territorial, often performing long aerial chases if one male encroaches upon another’s territory. All this territorial defense can make for a whirlwind survey experience, as we hurriedly record information on each bird’s location and movements. It is meticulous work (and will often lead to a bit of blood loss if you forget your mosquito net!), but in my 3^rd year of conducting this survey, I am more familiar with Bobolinks’ behaviour patterns, and it is becoming easier to keep track of “who’s-who” in the field. Fledglings have been detected in early to mid-July for the past three seasons, and their presence is a rewarding confirmation of successful breeding. Soon after the fledglings are capable of short flights, the birds begin to congregate in post-breeding flocks. By the middle of August, the Bobolinks have departed and it’s time to analyze all the data collected over the season.

 

This year, we have documented seven males and six females within the study area so far, and paired females should be finishing their nests and beginning to lay eggs by now.  Last fall, after several consecutive years of Bobolinks successfully breeding within the area, CVWMA made the decision to expand the pasture managed exclusively to benefit Bobolink habitat. On our most recent survey, we were excited to see two males already exploring the new expansion. We look forward to seeing how the birds will utilize this space over the season – stay tuned for an update this fall!