Brewer’s Blackbird

Named after the ornithologist Thomas Mayo Brewer, the Brewer’s Blackbird is a common and noticeable species originally found in western North America. Brewer’s Blackbirds lead quite interesting lives, let us take a dive into their background information and learn about how exactly this species operates. 

About Brewer’s Blackbirds

Over the span of 4 decades beginning from their first recorded discovery, the species expanded their nesting population rapidly and can now be commonly found in the south-eastern United States. Owing to the ease at which they are studied, Brewer’s Blackbirds have often been used as a subject model to evaluate hypotheses concerning behavioral and evolutionary ecology.

While this species can often be confused with Rusty Blackbirds, the former glossier coats and have a distinctively contrasting violet gloss on their heads with a green-tinted gloss present on their remaining plumage, in comparison to the latter which have no contrasting gloss. Brewer’s Blackbirds also have shorter bills.

These birds seem to live quite an interesting life, do they not? The more we dive into the workings of Brewer’s Blackbirds, the more we come to understand their intriguing behavior. For the purpose of educating ourselves on this species, here is a list of topics that we’ve explored in regard to Brewer’s Blackbirds. 

● Brewer’s Blackbird Photos, Color Pattern, Song
● Brewer’s Blackbird Size, Eating behavior, Habitat
● Brewer’s Blackbird Range and Migration, Nesting

Brewer’s Blackbird Color Pattern

The color pattern of Brewer’s Blackbirds can vary depending on the sex and the breeding status of the species. During the breeding season, adult males have black plumage, a glossy purple head, and a bluish-green gloss on the rest of their bodies. On the contrary, adult females have a brown and gray plumage. The males have the slightest hint of the same glossy colors. 

First-year males look similarly to adult females, with a brownish-black plumage and a weaker gloss. Adults have black feet and legs. While adult males have bright yellow eyes, adult females have dark brown eyes.

Male juvenile Brewer’s Blackbirds have dark and dull brown upper parts, including their wings. Their underparts are brownish-grey, closely resembling basic female Brewer’s Blackbirds, sans the iridescence and gloss. Female juveniles are identical to their male counterparts but are a lighter shade.

Although extremely rare, partial albinism has been spotted in this species. In an instance, around 40% of a flock of 500 Brewer’s Blackbirds have spots of white or white feathers.

Description and Identification

One of the most identifiable features of Brewer’s Blackbirds is the purple and blue-green iridescence spotted on their heads. While it is mostly in adult males during the breeding season. Adult females and year-old males also have the same iridescence, albeit slightly more difficult to spot. 

They often appear as small, healthy-size birds with a round head, a black bill, and short black legs. Their eyes are bright, contrasting shades of yellow in comparison to their dark or dull plumage.

Adult male Brewer’s Blackbirds have yellow, round irides, which can appear white under strong lighting. A majority of females have brown irises, but a tiny percentage of females in Wisconsin have yellow irises. 

Brewer’s Blackbird Song

Prior to or during hatching, there is no recorded information regarding their vocalization. However, after emerging from their eggs, they begin to make “peep” noises, which eventually evolve into “Tutz-utz-utz”. After 7 days of age, they make squawk in harsh, short notes in response to being provoked.  

Brewer’s Blackbirds are frequently sounding songs, alarms, and warning calls to deter predators, in their daily lives. They sing while perched in trees, shrubs, telephone poles, power lines, fences, on the ground, and mid-flight.

Across the 2 sexes, Brewer’s Blackbirds produces a range of calls and only 2 songs, most of these being shared. A few, however, are indeed unique to each sex. Males sing more frequently, despite both sexes knowing only 2 basic song forms. A short half-a-second “Schl-r-r-r-up” is sounded all year long, with the frequency of it increased during the breeding season. Many variations of this are found differing between each bird. 

Male Brewer’s Blackbirds often perform undirected songs, and during the female guarding period, they sing at a higher rate of frequency in an attempt to establish dominance and reduce the chances of cuckolding from other males in the area. In California, they practice polygyny to sing during a settled male’s incubation, in hopes of attracting an additional number of females.

Brewer’s Blackbird Size

Brewer’s Blackbirds are medium-size and are about the size of Red-winged Blackbirds. They can be the average size of Robins. Males measure 8.3-9.8 inches in length, 2.1-3 pounds in weight, and 14.6 inches in wingspan. The females average around 7.9-8.7 inches in length, 1.8-2.4 pounds in weight, and 14.6 inches in wingspan.

Brewer’s Blackbird Behavior

Outside of the breeding season, Brewer’s Blackbirds cluster together in flocks, and may even spend winter mixing in flocks with other blackbird sub-types. You’ll find them foraging around farming and agricultural areas, gathering around farm machinery to grab food turned up by plows, choosing to feed on the ground. They tend to perch on higher areas when resting, however, on objects such as power lines or telephone lines. Their diet mainly consists of seeds, berries, and insects, due to which, they may also be present around areas of shallow water.

Their walk resembles that of a chicken’s, their heads jerking with each step. When they fly in flocks, their bodies rise and fall along their journey, and may circle at a slow pace when attempting to land. When meeting predators such as Hawks, Gulls, or Owls, they sound an alarm call and dive at them, in an attempt to have them depart. During nesting season, Brewer’s Blackbirds will pair up, but discontinue association after it ends, but will reunite the following year if both birds return.

When Brewer’s Blackbirds sleep, they adopt a normal passerine posture. Their heads turning over their shoulders, while burying their staunch black bills in the crevice of their upper wings. They tend to find areas of shade when perching, even during the winter season or periods of cold weather.

Brewer’s Blackbird Diet

Similar to that of other Blackbird sub-types, Brewer’s Blackbirds enjoy a healthy diet of insects, seeds, and a few types of berries. They tend to flock around farm machinery in order to easily scavenge the food plowed up by the machinery present there. You may see them catch insects with their pointed beaks in-flight. They’re not picky with the type of insects they eat. Their diet may include grasshoppers, caterpillars, beetles, crickets, aphids, several types of spiders, and snails. 

Regarding seeds, Brewer’s Blackbirds will feed on seeds of grasses and weeds, as well as waste grain. During the summertime, the rate at which they consume berries is significantly higher, owing to the hot summer heat. Eating berries can give them a temporary cooling effect. 

Brewer’s Blackbird Habitat

Their breeding habitat is most often open or semi-open areas, located near the water all across central and western North America. Brewer’s Blackbirds may form nests in a variety of locations, such as in trees, in tall grasses, or on cliffs. Nesting takes place in colonies, as they are very social birds. Naturally, they may also gather around areas of density in context to humans, and are common in parking lots.

During migration, Brewer’s Blackbirds will take shelter in mixed flocks of other Blackbirds, in city parks or lawns. In open agricultural settings, they may rest in pastures, harvested, grain zones, orchards, meadows, livestock feedlots, along beaches connected to oceans, as well as lakeshores.

Range and Migration

Brewer’s Blackbirds are year-round residents, while only some migrate to milder areas, The ones that do, migrate during the daytime in both conspecific and mixed-flocks, joining other blackbird sub-types. However, they tend to be a tad bit reserved and distance themselves from other species, moving at the edge of a larger flock. 

Females are the more common sex in flocks wintering in Mexico. While males arrive several days earlier than females in Minnesota. This alludes to the possibility of some flocks being single-sex in terms of their composition. Depending on the area, females may arrive later than males at the breeding sites. 

Brewer’s Blackbird Lifecycle

Brewer’s Blackbirds lay eggs in batches of 3-7, with each egg averaging 0.9-1.1 inches in length and 0.7-0.8 inches in width. They females incubate the eggs for 11-17 days, and the nestling period lasts for around 14 days. The eggs themselves are colored green-grayish white, with spots or blotches of brown, yellow, gray, violet, and pink. 

The hatchlings emerge from the egg with their eyes closed, and naked save for sparse gray or black. Both the male and female Brewer’s Blackbirds provide food for the young, who then leave 13-14 days after hatching. Each pair of Brewer’s Blackbirds raise one or two broods every year.

Nesting

The placements of Brewer’s Blackbirds’ nests are found to be highly variable, ranging from areas of bright and concentrated sunlight to deeply shaded areas. One thing that remains consistent; however, is the presence of water nearby to the area where the nests are constructed. Water can mean streams, irrigation holes, and ponds.

The nests themselves are made from a combination of hair, rootlets, and dried grasses in some regions. In others, they’re found to be made from thick and bulky twigs, grass, mud, feathers, and manure. Over the span of 9 to 10 days, female Brewer’s Blackbirds will gather whatever materials they are able to find and construct the nests themselves, oftentimes without male assistance. 

Anatomy of a Brewer’s Blackbird

Brewer’s Blackbirds sexes are dimorphic in size. On average, they are small birds with round stomachs and heads. Their bills are thick, straight, and blunt, tapering to a point. Eye colors can vary, with male Brewer’s Blackbirds donning pale yellow irises and female Brewer’s Blackbirds having light to dark brown irises. However, it is important to note that a small percentage of the female Brewer’s Blackbirds are recorded to have pale irises. Immature males sport buffy feather tips on their breasts. These birds are a lovely sight to see for bird watchers. 

Final Thoughts

As the years have gone by, the expansion of the range of migration and habitat for Brewer’s Blackbirds have only gone up. They’ve been continuously expanding from western and central North America to the east, around the Great Lakes region. This allows for more opportunities to spot these little critters. You may find them perched in a nest on a tree, protected from the sun in a cool, shaded area, or you may find them gathering in groups in agricultural lands, foraging for food in the scraps left by farming machinery. This species is quite easy to spot and they present themselves in a myriad of areas, from crowded city parks to agricultural regions to cliffsides.

The purple and blue-greenish iridescence they sport is quite distinguishable, making it easier to discern them from other similar-looking bird species such as Common Grackles and Rusty Blackbirds. You may even spot them flying with these species, segregating themselves to the back of a flock, traveling together yet keeping to others of their kind. Their uniquely decorated plumage can be of aid to newly-declared bird watchers, standing out amongst other Blackbird sub-types. If you happen to ever find yourself in Western North America, do stop by the city parks to spot them.

Ornithology

Brewer’s Blackbird Bird Girl Videos

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The most common types of bird watching binoculars for viewing Brewer’s Blackbirds are 8×21 binoculars and 10×42 binoculars. Bird Watching Academy & Camp sells really nice 8×21 binoculars and 10×42 binoculars. You can view and purchase them here.

Brewer’s Blackbird Stickers

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Bird HousesForBrewer’s Blackbirds

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