Desert Nests

BY: HARRY L. and RUTH CROCKETT

Desert Nests STORY AND PICTURES BY HARRY L. AND RUTH CROCKETT

While it is still winter, nesting on the desert in Arizona is getting under way. This seems more reasonable when you realize that most annual plants are mature by mid-March and perennials are dropping their seeds by the end of May. The Costa's hummingbirds are courting early in February. Their courtship is a spectacular affair. She takes a place on a twig, usually at the side of a tree, and not too much in the open, while he takes to the air in a series of U dives. He reaches a height of eight to a hundred feet, turns and dives to a point just above her, ascending and diving, again and again. The air rushing through his wings and feathers produces a high pitched zing or hum. Estimates up to one hundred and twenty wing beats per second have been made for his wing motion in these dives. After the climax of the court-ship, he leaves the nest building, incubation of the eggs, feeding and training of the young to her. Mrs. Costa's nest is made of plant down, bound together with spider webs. She decorates or camouflages the outside surface with bits of leaves, flowers of the aster type, and other material giving it a rough, bunchy appearance. The house finches show favoritism for the chollas when they nest on the desert. They choose a spot toward the top where the angle between the trunk and branches gives ample space to construct the nest. The nest is made of green grasses. The first grasses are laid between two branches, making a pad over the spines and forming the base for the nest. The cup is then constructed on this with grass stems placed in a swirl, until the rim is of the desired height. These nests are built quickly and are still green when completed, but are left to dry and cure while the pair go through a short courting period. In the cholla blanca the grass so nearly matches the color of the cactus that the nest looks like part of it, giving the nest added protection. The eggs are bluish green with brown splotches on the large end. However, the eggs found in the desert nests are much paler than those in the irrigated areas. A complete clutch is five eggs and those are often ready for incubation early in April. House finches do not share the incubation duties, for the male's bright colors would be noticeable to their enemies. The female is a neutral gray in color, and will sit tight when you approach the nest, often leaving only when you reach to touch her. After the babies are hatched, he does a good job helping her feed the young. Several pairs of house finches build in a location, not too close to encroach on each other's feeding territory, but close enough for sociability.

The cactus wrens are nest specialists. They build a shelter nest for winter, starting it when the first cool evenings of October remind them that winter is coming. This nest makes a migration unnecessary; the days are usually temperate; only at night does the temperature drop so they need protection. It is a tunnel of spun straw, lined with material that is available. Feathers are used during hunting season. After sheep have grazed through their area, they gather wool that has been caught on barbed wire and thorns. Cotton is favored, when the nest is in flying distance of a cotton field. Any of these soft materials used as a padding, makes a warm shelter. The first week in April is the time cactus wren nesting is at its height. The incubation nest is similar to the shelter nest, although generally lighter in construction. Not being satisfied with one nest at this time, two or three are built in the vicinity. The spares are called dummy nests or cock nests. The number of nests lead the early bird observers to think the cactus wrens nested in colonies. The spare nests serve to confuse their enemies and are used as shelters and roosting places for the young after they leave the incubation nest. Cactus wrens select a spot at the top of the chollas, but also build in mesquite, iron-wood, and palo verde trees. The third and lower level of the cholla is used by the Palmer's thrashers. Their nest is made of sticks an eighth to a quarter of an inch in diameter, which are piled to form a bulky but substantial structure. The center of this is lined with fine grasses. The Palmer's thrasher's eggs are blue green, finely spotted with brown. There seems to be a correlation between the number of eggs a bird lays and the amount of rainfall the previous winter. Of course good rain-fall means more vegetation, and it does take considerable moisture in the body of the hen to produce an egg. Good years we find up to five eggs, poor years as few as two eggs. Bendire's thrashers are often found in the same zone, and the nests of the two species are very much alike. The eggs are easily identified as the ground color of the Bendire's eggs is buffy, with brown spots. The mourning doves build on the desert in three loca-tions. The tree sites, where a few sticks are laid across the fork of two branches, with practically no lining. Often you can look up from under the tree and see the two white eggs through the bottom of the nest. A second site, on the top of a caved-in cactus wren's nest, is converted by adding the usual few sticks. The third preference for a nest site is the ground. These nests are usually built between two rocks, eighteen or twenty inches apart. This appears to be a danger-ous location for a bird, requiring fourteen days to develop after hatching, but observation shows the young are success-fully raised in these nests. The giant or Saguaro cactus with its great variety of shapes and twists, furnishes sites for many birds. The one most noticed is the Gila woodpecker. These woodpeckers make a typical nest of their kind, a round hole opening into a pouch below. This is dug out of the body or arms of the cactus. The giant, reluctant to give up its moisture, seals over the injury with a scar tissue, which becomes permanent, and makes the opening a lasting contribution to the nest sites on the desert. We have found other birds, the Saguaro screech owl, elf owl, Arizona crested flycatcher, and western sparrow hawk, using these nest holes. The Gila woodpecker's eggs are white, as is the case when eggs are laid in holes. The Mearn's gilded flicker makes a similar hole in the giant cactus and about the only way to distinguish the nest is to observe the owners come and go. The giant offers another type of nest site to the red-tailed hawks. They select an opening between and arms and trunk of the cactus to deposit a great pile of sticks, some as large as a man's finger. This platform is then rounded up with a rim, and lined with grasses. They lay two to four white eggs, blotched with several shades of brown. Their habit of laying a new layer of sticks and a new lining, on the old nest be-fore housekeeping at the old stand, seems characteristic. Several years of observing red-tailed hawks nests brought surprises. At times, other birds confused the issue by taking over earlier, and the eggs or young of the great horned owl were found in the nests that in previous years had cradled young red-tailed hawks. The owl eggs are rounder and white The gnatcatchers are tiny fellows, little larger than the common hummingbird, although they look more like miniature mocking birds. The plumbeous gnatcatchers nest late in April. Their structures, similar to but larger than hummingbirds nests, are made of plant down and spider webs, with fragments of other materials on the outside. They favor a spot where several branches fork, in a thorny tree. The iron-wood is a favorite. Their eggs are a dull white spotted with brown.

The Arizona verdin, a desert bush-tit, thinks it better to build a shelter nest for winter than to migrate. The shelter nest is a hollow ball, made of small sticks and lined with grass and feathers. They prefer a bush or tree with thorns and use thorny sticks for construction. The shelter nest is made as a bed chamber for one bird. The verdin's brooding nest, finished in March, is larger than the shelter nest.

The cañon wren, heard singing from a canyon wall, is often the most thrilling part of a desert trip. As an introduction, he is the small brown wren that sings with a burst of ringing notes, on the decending scale. Their choice of nesting sites is very erratic. We have found them in the banks of washes and in buildings. The last nest we found was in a giant cactus. The cavity was made by an injury to the cactus, and holes between the exposed cactus ribs were utilized by the wrens as entrances. Their eggs are white, well covered with spots of brown and lilac, and are laid in a nest of small sticks, leaves, grass, and feathers.

The phainopeplas, among the few birds that carry the first part of their proper name as a common name, are usually without blotches.

Also found in greater numbers when the mistletoe, the variety which is a parasite on the trees of the desert, has been bountiful. These black fellows, with the high loose crest, build their nests in the desert trees. These nests, usually well concealed, seem small and insignificant in comparison with the striking beauty of the bird in flight. Nests are made of twigs, with a deep lining of plant down. The two or three eggs are light gray, spotted with brown. The young, in dark gray plumage, are in the air in early May.

The orioles, and there are three species: Scott's, Arizona hooded, and Bullock's, are found on the desert, but their preferences are for higher parts. They like the canyons with trees, or the desert where water can be found, at watering troughs or homes. The fiber of the yucca is utilized in weaving their hanging cradles, but they will also use horse hair or strings. These structures are carefully woven and depend on a collar for strength. The oriole's nest are able to withstand strains from outside as well as from within, and are top level bird structures.

Gambel's quail is a ground nester, utilizing a clump of grass or similar cover for the nest, which is comparatively large. The ground birds have a high mortality, so have developed the trait of laying a large clutch of eggs. The female quail deposits as many as nineteen eggs. She does the incubation, but the male will take over in case an accident prevents her. The young, as is the case with most birds that have been ground nesters for many generations, are able to follow the parents a few hours after hatching. The male is a good parent and works diligently to provide a living and to protect their brood.