Abstract
One of the most strikingly beautiful native species, the Yellow-headed Blackbird is distributed over the marshes of western North America, from Canada through southern Mexico.
Up to 11 inches long, with the females being significantly smaller, the handsome males are basically black with a bright yellow (sometimes '' orangey") head, neck and upper breast, and sporting a small white patch on the primary coverts. The hens are dark brown with yellow throats and no wing patch.
The extraordinary voice as described in the Audubon Society Encyclopedia of North American Birds, is a '' cacophonous series of high pitched liquid and clacking notes, the last a drawn out buzz or squeal'.' The call note is a low, hoarse Ka-ak. A common and highly visible resident of the estuaries and marshes around the Great Salt Lake, nestlings were first collected under state and federal permit by Tracy Aviary in June of 1986.
Mark Stackhouse, an avid birdwatcher and Aviary Education Coordinator and I went out into the closest marsh only ten minutes from the City Center and located a small colony without any difficulty.
Laying claim by seniority and speed to the only non-leaking pair of waders, I plunged into the rather foetid atmosphere of the tall reeds and razor-edged grasses housing the large and untidy accumulations of dead grass and detritus, which constitute the blackbirds' nests.
Mark squelched into the reed patch some distance away and could be heard to be relishing the surprisingly cool water leaking onto his cotton socks, though he was the first to locate a nest with half grown young.
We collected three chicks on that occasion and three subsequently, each chick from a separate nest. Almost all of the nests held either three eggs or chicks at various stages of development.
The chicks collected were all about a week old, eyes just starting to open and pin feathered (we felt that older chicks were less likely to adapt and younger ones were too vulnerable and delicate). All of the nests and chicks supported substantial louse populations. I shall always remember struggling to the water's edge through the Turkish Bath atmosphere of the marsh (the temperature was over 90°F), through the claustrophobic reeds and razoredged grasses, whilst sulphurous gases erupted from the marsh with every footstep and lice paraded all over my hands and arms. We deposited the chicks in tissue-lined boxes and hastened back to the water's edge to wash off the armies of invading ectoparasites.
On arriving back at the aviary, we first sprayed the chicks in their containers with a mite and louse killer before transferring them to a brooder. This was just an unused game-bird brooder with the temperature turned down to 85 degrees.
The chicks were very simple to rear, growing well and rapidly on a diet of soaked puppy chow, Bird of Prey Diet (Ziegler), mealworms, crickets and hard-boiled egg. As the chicks became independent, eating by themselves and acquiring their typical juvenile plumage of dull brown with a small number of yellow feathers on the throat; they were transferred to a larger holding cage, 8 feet high by 12 feet long by 4 feet wide, sparsely furnished with a perch at either end.
At about eight weeks of age, the birds were in perfect feather, flying strongly and totally independant. We then transferred them to our large flight cage, a 40 year old structure like an elongated dome, 100 feet long, 50 feet wide and about 40 feet high. The middle third is a shallow stream which flows across and through the aviary and in the center of which is a small island 12 feet by 8 feet, appropriately planted with coarse weeds and willow tangles. Other inhabitants of this cage...