{"id":2953,"date":"2019-11-22T17:36:47","date_gmt":"2019-11-22T17:36:47","guid":{"rendered":"http:\/\/wordpress.viu.ca\/biol325\/?p=2953"},"modified":"2019-11-28T01:31:21","modified_gmt":"2019-11-28T01:31:21","slug":"could-it-be-the-milkmans-baby-the-brown-headed-cowbird","status":"publish","type":"post","link":"https:\/\/wordpress.viu.ca\/biol325\/2019\/11\/22\/could-it-be-the-milkmans-baby-the-brown-headed-cowbird\/","title":{"rendered":"Could it be the Milkman’s baby?: The Brown-headed Cowbird"},"content":{"rendered":"\n

Marissa Wright-LaGreca <\/p>\n\n\n\n

I: Its a bird! Its a plane! Its a cow! Its a bird on top of a cow..? <\/h2>\n\n\n\n

Hello, welcome to the story of a bird’s life; Brown-headed Cowbird edition. On first impression, these strikingly plain birds seem fairly ordinary, however, the Brown-headed Cowbird requires a few dates to really get to know. <\/p>\n\n\n\n

Identification <\/h2>\n\n\n\n

 Fortunately, the name of the Brown-headed Cowbird (BHCO) is straightforward; Belonging to the Family Icteridae, adult males can be identified by their black body with a slight green sheen, and chocolate-brown head. <\/p>\n\n\n\n

\"Brown-headed
Figure 1: Adult male Brown-headed Cowbird (photo by Brian Sullivan<\/a>)<\/figcaption><\/figure>\n\n\n\n
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Figure 3: Juvenile Brown-headed cowbird (photo by S.K Jones<\/a>) <\/figcaption><\/figure><\/div>\n\n\n\n

BHCOs have a slightly pointed but stout bill. Molting juvenile males have patchy black and brown coloration. Adult females have a drab brown coloration with fine brown streaks down the belly and a whitish throat. <\/p>\n\n\n\n

\"Brown-headed
Figure 2: Female Brown-headed Cowbird (photo by Arlene Ripley<\/a>)<\/figcaption><\/figure><\/div>\n\n\n\n

Brown-headed cowbirds may look completely black in poor lighting, in which case they may be confused with other blackbirds. However, its conical bill (shorter than body), thick neck, large head, and smaller overall size (~40-50 g) can be used to distinguish it from other blackbirds (Cornell…2019)<\/a>.<\/p>\n\n\n\n

Another species of cowbird is the Bronzed cowbird. It can be distinguished from the BHCO by the adult male’s red eye, thicker neck, and glossy-blue wing color. The range of Brown-headed Cowbirds and Bronzed Cowbirds has overlapped, resulting in competition for host nests as both species are brood parasites (more on this later). Bronzed Cowbirds tend to parasitize larger birds than the Brown-headed, however, both eggs have been recorded to be in a single host nest (Cornell…2018)<\/a>.<\/p>\n\n\n\n

\"Bronzed
Figure 4: Adult male Bronzed Cowbird (photo by Brian Sullivan<\/a>)<\/figcaption><\/figure><\/div>\n\n\n\n

Feeding<\/strong><\/h2>\n\n\n\n

Classified as a ground forager, Brown-headed Cowbirds feed largely on seeds and insects. (Cornell…2019<\/a>). Insect consumption increases while breeding and is an important component of hatchling’s diets. <\/p>\n\n\n\n

In the early 1800’s, bison populations in North America were great (estimated 30 million) and were the main \u201criding hosts\u201d of the cowbird (Bison 2013<\/a>). As the bison population fell due to over-hunting following European colonization, cowbirds transitioned to horses and cows that grew increasingly abundant with agricultural expansion. <\/p>\n\n\n\n

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Figure 6: An adult male (left) and a female (right) Brown-headed cowbird sitting on a handsome cow (photo by San Diego bird spot<\/a>) <\/figcaption><\/figure><\/div>\n\n\n\n

 In a sort of cowboy-esque manner, cowbirds sit on horses and cows (hence the name Cow<\/em><\/strong>bird). As the cows graze, insects are stirred-up, enabling the cowbird to more easily spot its prey.       <\/p>\n\n\n\n

Habitat<\/strong><\/h2>\n\n\n\n

 Brown-headed Cowbirds occupy farms, fields, urban areas and semi-open habitats. They can inhabit a large range of areas, however, tend to avoid dense forests. Unbroken forests may deter Brown-headed Cowbirds as it is difficult to locate and stalk host-nests under dense foliage. Habitat fragmentation has aided in the dispersal of Brown-headed Cowbirds. (Cornell…2019<\/a>) <\/p>\n\n\n\n

Sounds<\/strong><\/h2>\n\n\n\n

The male Brown-headed Cowbird sings a uniquely distinct song that is attractive to female BHCOs. The song is filled with gurgling notes and thin whistles. The song sounds as if the cowbird is taking a big swig of water, however, the video looks more as if he is throwing up water. As the bird sings, he puffs out his chest and feathers:<\/p>\n\n\n\n

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