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THE BIOLOGY AND NATURAL HISTORY OF THE MOURNING DOVE
[Presented by Wilmer J. Miller, 16 January 69, at a public forum on the question "SHOULD DOVES BE HUNTED IN IOWA" sponsored by the AMES AUDUBON SOCIETY]
The mourning dove, Zenaidura* macroura, belongs to the order Columbiformes, family Columbidae and subfamilly Columbinae. The whole order of Columbiformes is unique among birds in being able to drink water in a continuous draught, like a horse, and in producing "pigeon milk", which is fed to the young by regurgitation. All birds in this order are commonly called pigeon or dove--usually the term pigeon us used for larger species and dove for smaller ones.
The closest relaltive of the mourning dove is Grayson's dove of the Socorro island of western Mexico. Z. auriculata of South America is next in kinship. Probably the much larger but extinct passenger pigeon was the next most closely related species.
Mourning doves weigh 4-6 ounces, usually close to the lesser weight. They are bluish gray above and tannish gray below with black spots on the wing. Mutant color variants are not generally encountered but albino, pied, pale, dilute, and reddish forms have been noted. They are nearly 12" long, about half of which is tail; and the tail is strongly graduated having 14 feathers instead of 12 as most dove species have. The F1 hybrid on exhibit here with the ring neck dove, Streptopelia risoria, has the 12 tail feathers of the ringneck but lacks the spots of the mourning dove as well as lacking the ring (color) or the ringneck dove. All such hybrids tested have been sterile in backcrosses to the ringneck dove.
In Iowa, mourning doves nest f rom about April to October. They seem to prefer nests in trees near human habitation, even when suitable trees more remote are available. They may nest, however, almost anywhere from on the ground to 90' high. Four to 8' above the ground is not unusual. They like American elms, red pines or any horizontal supporting area. In making the nest, they carry sticks singly, and often nest in an unused robin's nest.
Doves lay a clutch of two white eggs. The second egg is laid 40 or so hours after the first. The incubation period is 14 days. The "egg tooth" occurs on the lower as well as on the upper bill for some mysterious reason. The male usually carries the bigger shell part away from the nest and drops it. the young are altricial (helpless) at hatching in contrast to the precocial type of bird such as the chicken. The squabs are fed "pigeon's milk" (originating from the crop wall) by regurgitation the first few days, with seeds being mixed in rather early. The young grow rapidly (50% of the squab's weight may be food)--the eyes open about the 5th day--"wing fanning" may occur after the 9th day--they may leave the nest from some minor disturbance at 12-14 days of age, but they are not really independent of the parents until over 20 days of age. The juvenile feathers have a buffy gray border which is lacking in the adult.
The nesting success is about 50%, but is highly variable, Eggs and young may be lost to storms blowing the nest down or breaking them up under the setting parent. Five to 6 nesting attempts per season yield about 5 young fledged. Flocking in the fall occurs and the flocks grow larger as they move south. Iowa birds usually go to the Texas area.
The food is mostly seeds. In one major study by McClure it was found that more than 40% of the food by weight consisted of hemp seed from July to October. He attributed the high production of doves during a three year study in Cass country, Iowa, to the then abundance of hemp seed. Wheat and waste (cracked) corn are important in their diet, but the "natural" food is weed seed. The doves really eat large amounts of weed seed including foxtail, pigweed, etc. They may pick up 20-50 seeds per minute while feeding. they either find an outcrop rock containing a calcium source or else they supplement their diet with snail shells for this important mineral.
Predators other than man are cats, hawks, cats, owls, and CATS! Blue jays take nestlings, and jays and squirrels take eggs. Rats and snakes are much less important as predators. Men shoot them, boys may take nestlings and break up nests, but perhaps the worst loss is the cutting of nestling trees, which is more serious than most people realize.
The behavior of doves is quiet and unobtrusive. They seem to delight in "heteropreening" each other and their young for long periods, removing bits of dirt and feather casings. They keep very clean by preening and by bathing in rain or a shallow pool. They are really very pleasant to have about.
The voice of the squab is a high pitched whistle or trill, given with a wing shuffle in food-begging movements. Adults have a three-note nest coo, soft but carrying well, to encourage the mate to bring sticks, or for inquiry of the mates's whereabouts (?). Their attractive regular perch coo or courting coo is a five-note coo with a sixth delayed note often added. It is in a minor key and nearly mournful, but never too loud.
They form nesting territories, although several may nest in the same tree. When the territory is challenged they will fight with a strong wing slaps and pecking at the eyes and head or shoulders of the opponent. They have a warning note for cats or other dangers--a nearly harsh but soft "hnnnh". Young or even adults disturbed on the nest may hiss and puff, often adding a popping or snapping sound.
The flight is strong, silent when desired, or "whistle type" in display. When frightened on the gound, they leap into the air as they throw their wings above the back and bring them down with terrific force extending them outwardly. The tail is spread and tilted at different angles resulting in a zigzag flight up. Then they level off and fly away with irregular sideways swaying motions making them a difficult shot for hunters. Flight speed is about 35 miles per hour, but when pressed or diving they can exceed this speed considerably.
* * * * * *
I'd like to contrast deer and doves. The natural predators for deer such as wolves and cougars, are gone--man must substitute as a predator on deer, for if deer become too numberous, they will destroy their habitat. Doves, if too numerous, will not so destroy their habitat--and who ever heard of too many doves?
In my experience many hunters hunt doves just because they present a difficult shot; and the "hunter" may just leave them lie where they fall ( or later throw them away) because there is not enough meat, or it is "too much work" to prepare a few doves to eat.
*Now Zenaida is preferred as the generic name. And I might add the white winged dove and ground dove as relatives.
Independance at 20 days seems a bit early to me now for complete independence.
McClure, H.E. 1941 Ecology and management of the mourning dove, Zenaidura macroura (Linn.), in southwest Iowa PhD thesis ISC pp 366
Eds. Baskett, Thomas S., Mark W. Sayre, Roy E. Tomlinson and Ralph E. Mirarchi
ECOLORY AND MANAGEMENT OF THE MOURNING DOVE, a Wildlife Management Institute Book 1993 Stackpole Books, Harrisburg, PA, 567 pages Price $50.
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