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Winging It - Tropical Birds Arriving in Sonoma County this Summer


Winging It - Tropical Birds
Arriving in Sonoma County this Summer

By Lisa Hug - the Bird Lady

Sonoma County has birds that stay her year-round (permanent residents) and birds that migrate here from tropical areas of Central America during spring months to take advantage of  our longer sunny days of summer (neotropical migrants).  Most of our permanent residents, like titmice and sparrows are some shade of gray or brown.

But summer is the time of year when we are blessed with a little splash of the Tropics. When we think of tropical birds, we think of color – macaws  toucans,  trogons, quetzals, and  ---  orioles. Most of these bird species stay in the tropics year-round.   But, as the days lengthen in the spring, a few birds have to obey their roiling hormones telling them to “go north.” 

You might wonder why these birds would risk their lives to fly such  long distances to rear their young. But our long summer days give the birds more time in which to feed themselves and gather food for hungry nestlings.  There is also less competition in these mid-latitudes because there are fewer birds here than in the Tropics.

So, around mid-March, we start to notice the arrival of colorful birds –blue ones, yellow ones, orange ones.  And amongst the most colorful of these neotropical migrants are the orioles.

Hooded OrioleWe are lucky to have two species of orioles here in Sonoma County – the Hooded Oriole and the Bullock’s Oriole. Both of these orioles come in stunning shades of orange, with black accents.  The male Bullock’s Oriole has a black back with a prominent black eye line and a long, thin, black “beard.”  The male Hooded Oriole has an orange head and back with a square black “beard.”

Orioles are not only colorful, but they are talented architects.   They weave intricate nests.

The Hooded Oriole prefers to weave its nest amongst palm fronds.  The female pierces the palm frond with her bill and then pushes  strands of palm fiber through the holes.  She literally sews her nest to the frond. They sometimes make extra nests.   This might be to confuse predators.  House Finches will sometimes skip making nests themselves and just raise their young in  one of these “pre-fab” nests.

Hooded Orioles are a relatively recent addition to the birdlife of Sonoma County.  People  first noticed them here in the late 1970s.  In the 1920’s Hooded Orioles only ranged as far north as Santa Barbara County.  By the 1940s, they arrived in Marin County. This is  a natural northward range expansion from southern California is mostly credited  to planted palm trees.  They also benefit from fruit trees, ornamental shrubs  and hummingbird feeders.  Therefore, they tend to be an urban bird.

Oriole FledglingBullock’s Orioles are common nesters along riparian corridors.  It can take a female Bullock’s Oriole up to 15 days to weave her elaborate structure.  She usually uses grasses,  plant fibers, and animal hair.  But it is not unusual for her to seek out sturdier,  manmade materials.  She  frequently uses twine, fishing line, Easter grass, electrical wire, and anything else that she finds interesting . 

She makes a hanging pouch about six inches long. These nests can be spotted during winter months, in leafless trees. Sometimes she will re-use materials from one nest to make a new nest.  But she won’t re-use the nest from year to year. 

Bullock’s Orioles are always on the lookout for interesting nesting material.  And they aren’t above stealing it from other birds’ nests.  Just this spring, a group of birders and I were at a local park.  A Western King bird was building a nest near the park restrooms.  It had found a large quantity of bathroom tissue with which to line its nest.  When the nearby Bullock’s Oriole saw this, she HAD to have it.  Every time the kingbird left its nest to gather more material, the oriole would take the bathroom tissue from the kingbird nest, and add to its own.

Oriole NestFeeding: It’s wonderful to have orioles here in the summer.  You can enjoy them in your  own yard with hummingbird feeders, or specialized oriole feeders (with larger holes and perches) or by putting out dabs of grape jelly.  However, if you use feeders, be sure to keep them clean and sterile.  Many Bullock’s Orioles will slip out of northern California to return to Central America in July.  But the Hooded Orioles tend to stay a little later in to August or September, but they are more dispersed once the young fledge from the nests  - usually in June and July.

So, be on the lookout for these dazzling orange visitors in your neighborhood this summer!

Pleasants, Barbara Y. and Daniel J. Albano. 2001. Hooded Oriole (Icterus cucullatus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: doi:10.2173/bna.568

Rising, James D. and Pamela L. Williams. 1999. Bullock's Oriole (Icterus bullockii), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: doi:10.2173/bna.416

Parmeter, Benjame D. and Bolander, Gordon L.  Birds of Sonoma County California. 2001.  Redwood Ornithological Society.  Napa, CA.