Article for September - October 2007
by Rick Leonardi
Ongoing dove-banding research guides biologists in keeping mourning dove populations strong.
Because we meet only on the occasion of the first dove shoot of each season, I had not seen Neil O’Shields for a year. He is a very good shot. He sits in the shade, downhill from the sunflowers and millet, and takes his limit of twelve in short order if we have any birds at all, and we typically do. Two years ago he approached me during the barbecue phase of this fine tradition and said he wanted to show me something. At his truck he produced an envelope and carefully removed a tiny aluminum band, on the order of what we might find on a duck, but much smaller.
He said with a broad grin, "I killed a banded dove last year. I didn’t even realize it till I was cleaning them for the freezer, and there it was. I’ve never seen one before, have you?"
I admitted I hadn’t, didn't even know doves were banded, and wondered aloud what it was all about.
Now, I know.
It’s research, a study being conducted here in South Carolina and in more than thirty other states, intended to guide wildlife biologists in their management of mourning dove populations. Each year, between July 1 and August 15, doves are live-trapped, banded and released with the hope that hunters harvesting these birds will report the recovery of the band and provide details as to when and where the harvest took place.
Under the direction of Billy Dukes, Small-Game Project supervisor for the S.C. Department of Natural Resources, the agency participated in a pilot study launched in 2003 in collaboration with the U.S. Fish and Wildlife Service and the U.S. Geological Survey. In 2004 an incentive was offered to hunters who reported the collection of a band—a reward substantial enough, biologists believed, and I’m sure they were right, that the rate of reporting would be at or near 100 percent. The reward is no longer offered, but reporting has been made easier through a toll-free number stamped on the band. The calls roll in each fall, and the participation of the hunting community is absolutely vital to the success of the program.
Dove populations represent a very fluid resource. Each fall their numbers peak at what biologists estimate to be between 400 and 475 million birds nationwide. Sounds like a lot, doesn't it? When we consider, however, that 70 to 80 percent will not see the next breeding season, a half-billion becomes a less impressive number. The research being conducted by Dukes and his counterparts around the country is vital to determining the means of sustaining a healthy, stable population.
Many factors combine to cause this high mortality rate, and hunting is merely one of them. Based on harvest studies, Dukes estimates the number of mourning doves killed by hunters each year at around 20 million, perhaps a million of them here in South Carolina. So, the other 300 million-plus die of natural causes.
Those of us who have observed the nesting habits of the mourning dove know without doubt they slept through their structural engineering courses. Their nests are flimsy, often abandoned by other birds and precariously lodged in unsuitable places. Severe weather, especially high winds, will certainly affect the success of a breeding pair in bringing a clutch of two eggs to fledgling age.
Two factors work in their favor, however. Both the male and the female are doting parents who work hard at raising their young, feeding them "crop milk," a combination of crushed seeds and shed epithelial tissue from their crops. This potion, rich in protein, produces fledglings in about two weeks.
Then the second positive factor comes into play. On becoming empty-nesters, the mated pair soon begins the process of procreation again. If successful, two more young mourning doves join the population in about twenty-eight days. And then, the process is repeated. Throughout a long mating season, these birds are happily enthusiastic, if untalented, breeders and multiple clutches are the rule. Nesting success is placed at around 50 percent.
If, however, severe weather in the form of heavy rain or high winds plagues the breeding area, the success rate will plummet. Thus, the need for long-term research and careful management is established and inarguable.
A team composed of members from the DNR's Wildlife Section—Regional Projects and State Projects, as well as the U.S. Fish and Wildlife Service, has, since 2003, banded more than 5,600 doves here in South Carolina and received reports on exactly four hundred bands. This recovery rate of 7 percent is roughly consistent with national results, according to David Otis, of Iowa State University, the national coordinator of the dove-banding and population-modeling project. Trapping is accomplished with baited funnel traps for a six-week period between July 1 and August 15. The traps are monitored carefully for signs of predation, which can dramatically influence the success of a bait site. The sites are distributed around the state on private farms and public lands such as Santee Coastal Reserve, Bear Island WMA and the Webb Center.
Here is what analysis of the recoveries has established:
Our doves are just that, our doves. They are homebodies, rarely moving more than five miles for food and water, and typically do not migrate but move laterally within the state. A few notable exceptions: While 93 percent of band recoveries have occurred within our boundaries, some few have ventured out to places such as Jackson, North Carolina (278 miles), Moultrie, Georgia (301 miles) and LaBelle, Florida (493 miles). The record-holder, and feathered version of Wrong Way Corrigan, was a bird harvested in North Judson, Indiana some 600 miles in the wrong direction. What was that bird thinking about?
We have hosted, if somewhat harshly, birds banded in other states, as well. Louisiana, Missouri, Arkansas, Maryland and Pennsylvania have contributed to the harvest here in South Carolina.
Of the four hundred South Carolina bands recovered, 88 percent fell into the hands of hunters in the earliest dove season, and the vast majority of all recoveries, 85 percent in some years, were juveniles, which biologists refer to as “hatch-year” birds.
Though, as in many species, the first to go are the young and untried, consider that a long-lived dove dies within two years of hatching.
So, given the vagaries of habitat, weather, nesting habits, determinate clutch size (two eggs only), brief life span, high natural mortality and myriad other factors over which even learned and dedicated biologists exercise no control, merely one means of influencing the success of these wonderful birds exists. Dove management is harvest management, estimating the number of birds killed by hunters each year and ensuring the level of harvest is appropriate for sustaining a healthy population. Banding is a critical and indispensable tool toward this end.
Inasmuch as doves are technically migratory, seasons and bag limits are federally mandated and vary minimally from state to state. Simply, we hunt for sixty days and observe a daily limit of fifteen birds, or enjoy seventy days of hunting for a daily limit of twelve. South Carolina has opted for the latter combination.
Wing studies from captured and hunter-killed doves also provide valuable information regarding their ages. Integrating these findings with statistics from the banding study allows biologists to determine how successful hatch-year birds have been in joining the population. These recruitment levels will ultimately help biologists develop accurate population models and effectively determine responsible and appropriate harvest limits.
Billy Dukes not only guides the state’s efforts in this research but also plays a national role as the DNR representative on the Eastern Management Unit Dove Technical Committee. His efforts and those of the many participants from state and federal agencies are dedicated to preserving this marvelous resource and ensuring the future of dove hunting.
Those of us who love the September tradition of barbecue, birds and ballgames on the radio in the hot South Carolina sun reap the benefits of this work.
Rick Leonardi is a free-lance writer living in Charleston.
© 2007 South Carolina Wildlife Magazine - www.scwildlife.com