Today we meet the blue grosbeak. This little songbird is a sometimes resident, sometimes migrant whose coloration has direct effects on its ability to welcome baby blue grosbeaks into the world.
The blue grosbeak’s scientific name points out the importance of updating your bird book collection with the newest editions. My go to Costa Rica bird book claims its scientific name is (Guiraca caerulea) and for quite a stretch of time that was true, but after some studying of its mitochondrial DNA in 2001 the people that decide these types of things concluded that (Passerina caerulea) was more accurate. Trust me, you don’t want to publish an article about birds with an inaccurate scientific name, the birders will come for you. The Spanish name, picogrueso azul (translates to blue thick-beak), seems to have remained consistent over time.
Male blue grosbeaks live up to their names, they are a very pretty shade of bright blue. Female blue grosbeaks on the other hand are a very everyday shade of light brown. Both sexes have large, thick beaks and cinnamon wing bars that aid in identifying the species.
The pattern of males looking fancier than females is a common one in the bird world. It’s thought that males try to outcompete each other with fancy feathers and bright colors, while the more plain-colored females do the mate choosing. Well, some researchers dove headfirst into studying this hypothesis while researching blue grosbeaks in Alabama, and their results were fascinating.
They studied the offspring in these supposedly monogamous birds’ nests and found that many nests contained chicks that weren’t fathered by the male in the pair and more dull colored males had a larger percentage of ‘some other guy’s chicks’ in his nest than brightly colored males. So brightly colored blue grosbeaks were more successfully passing on their genes to the next generation than dull blue grosbeaks.
Costa Rica is home to a resident population of blue grosbeaks in the northern Pacific and western Central Valley. The population is augmented by migrants from the north from October to April. The migrants join the resident population and can also be found along the Caribbean coast.
If you’re looking for blue grosbeaks, you want to avoid thick, mature forests. These birds prefer agricultural areas, areas with scattered trees and thorny brush, and the edges of forested areas where they hunt for seeds and insects.
I’ve seen blue grosbeaks a handful of times in Guanacaste. I have a special place in my heart for blue birds after living in Pennsylvania, home to the eastern bluebird, so seeing these bright blue songbirds always makes me happy. I’ve recorded them a few times with camera traps, always while visiting a dry season puddle of water in Guanacaste. Take a look at a few of those clips in the video below.
About the Author
Vincent Losasso, founder of Guanacaste Wildlife Monitoring, is a biologist who works with camera traps throughout Costa Rica. Learn more about his projects on facebook or instagram. You can also email him at: vincent@guanacastewildlifemonitoring.com
