Wednesday, July 18, 2018

Great-tailed Grackle at Dixon Lake

Grackles tend to be noisy and somewhat obnoxious residents of parks, lake shores, and parking lots. Great-tailed Grackles are found from Texas to California, never far from water... or people.

Great-tailed Grackles first arrived in San Diego County in 1977, but were not noted breeding until 1988. By the time of the publication of the San Diego County Bird Atlas (2004, Philip Unitt) birds were locally common throughout most lowland wetlands and lakes.

These birds are fairly common at the golf course across the street from my home and nearby at Dixon Lake. They were not recorded there during the Atlas project. So, they have continued to expand until it would be unusual to find a lowland lake with manicured lawns that did not support a colony of these birds.

The male pictured below was "singing" last month on the shore of Lake Dixon, in Escondido. The display is quite involved and includes spread tail, slightly open wings, and head throws with loud squeaks, rattles, squeals, and whistles.

Great-tailed Grackle
Great-tailed Grackle. Dixon Lake, California. June 15, 2018.
Take another look at the bird below. See the dark and light bands on the feathers of the tail? These are growth bars. Dark bars are daytime growth and the pale bars indicate night time. Each pair is a day of growth. How many days did it take to grow the longest tail feather? (I count over 30 pairs of growth bars in the longest feather.)

Grackles are quite unique in molting all their tail feathers at once, thus being tailless in late summer. The tails of grackles will have all feathers showing the same wear and fading, as they are all the same age. Most other birds molt the tail sequentially (or in groups of 3-4 feathers at a time), thus would show groups of feathers with differing wear and fading patterns as adults (> 1 year old).

Great-tailed Grackle

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