Proceedings of the Thirteenth Vertebrate Pest Conference (1988)

CONFERENCE PARTICIPANTS: Thirteenth Vertebrate Pest Conference

Fri, 15 Jul 2005 08:20:16 PDT

The Conference totalled 401 registered attendees. The wide representation from the United States and from 14 countries throughout the world contributed to the success of the Conference by providing a highly diversified group for the exchange of ideas and information.

CLOSING REMARKS FOR THE THIRTEENTH VERTEBRATE PEST CONFERENCE

Lewis R. Davis — Fri, 15 Jul 2005 08:17:47 PDT

This brings to an end the Thirteenth Vertebrate Pest Conference. Without the speakers and the session chairs, there would not have been a conference. Let us acknowl�edge them for the excellent job done.

BEHAVIORAL RESPONSE OF CATTLE EGRETS TO POPULATION CONTROL MEASURES IN HAWAII

David P. Fellows — Fri, 15 Jul 2005 08:15:29 PDT

We monitored behavior of cattle egrets (Bubulcus ibis) during a population control program to reduce egret-aircraft strike hazards from a small heronry near the Hilo, Hawaii, airport. Results verified that attempts to move egrets from undesirable roost sites should be undertaken before nesting begins. Although possibly compounded by previous treatments, our observations also indicate that 1) egrets may abandon a new roost in response to a few dead egrets placed in clear view around the roost, and 2) shooting at egrets as they attempt to land at a traditional feeding site causes long-term avoidance of the area. Rapid repopulation after control indicates that techniques to move roosts and prevent congregations are more likely than population control to resolve problems.

INNOVATIVE APPROACHES IN THE CONTROL OF QUELEA, Ouelea auelea lathimii. IN ZIMBABWE

Mike LaGrange — Fri, 15 Jul 2005 08:09:13 PDT

Ever since crops have been grown, quelea have been a threat to summer subsistence crops and winter commercial wheat/barley cropping in Zimbabwe. Control techniques spraying toxicant Queletox through ground spray units and aircraft, developed in Zimbabwe, have produced 90% kills keeping the level of depredation down to acceptable levels. Zimbabwe, like most developing countries, faces protein shortages, and utilization of dead quelea by the rural population has always occurred even from sprayed colonies despite repeated warnings of possible side effects. Traditionally quelea have been sold on the black market for 10-20 Zimbabwe cents/bird and recently a far wider potential, even export, has been realized with a potential value increased to 40 cents/bird. Several applications for permits to harvest large numbers have been processed by the Department for export and local consumption provided a suitable method of capturing large numbers could be perfected. The recognition of quelea as a potentially economic renewable resource has intensified research in this area and several mechanical systems have been tried over the years finally culminating in the promising development of the "Impact" trap. The method potentially provides large numbers of uncontaminated quelea for the market. With careful monitoring and the parallel development of the trap roost concept, it is possible this approach could also sufficiently reduce toxic control beneficial to the environment as a whole while providing a source of food and revenue to Zimbabwe.

CHARACTERISTICS OF BIRD-RESISTANCE IN AGRICULTURAL CROPS

Roger W. Bullard — Fri, 15 Jul 2005 08:04:56 PDT

The use of biochemical or morphological genetic traits in a crop to protect ripening seeds or grain from bird damage remains a promising tool under certain situations. Research on bird-resistance in crops has focused on grain sorghum, corn, sunflower and rice. This crop protection method involves feeding behavior of granivorous birds and its effectiveness depends on the availability of preferred alternate foods. That is, bird-resistant traits provide protection to the crop when other food choices are readily available; however, when alternate food is scarce or high bird populations create serious feeding competition, they are less effective. Several practical factors (i.e., efficacy expectations, agronomic considerations, and cost-effectiveness) were discussed that should be considered in adopting this bird damage control strategy.

ALLEVIATING NUISANCE CANADA GOOSE PROBLEMS WITH ACOUSTICAL STIMULI

Donald F. Mott — Fri, 15 Jul 2005 08:01:45 PDT

Alarm/distress calls of Canada geese (Branta canadensis) were evaluated by themselves and in combination with racket bombs to determine their effectiveness in frightening Canada geese from nuisance situations at 2 Corps of Engineers campgrounds in Tennessee. Results based on goose censuses showed a significant (P<0.05) reduction in goose numbers from nontreatment to treatment periods at both sites. Goose numbers were reduced an average of 71% when the calls alone were used. The combination of the calls and the racket bombs produced a 96% reduction in goose observations. Although a reduction in geese was observed during the treatment periods, continual harassment would appear to be necessary as reinvasion was noted after treatment was stopped. The scarcity of alternate feeding and loafing sites may have contributed to this lack of long-term control.

CONTROLLING SHINY COWBIRDS IN PUERTO RICO

Jon F. Heisterberg — Fri, 15 Jul 2005 07:56:32 PDT

A program to trap and remove shiny cowbirds (Molothrus bonariensis) was conducted during two successive passerine nesting seasons at Roosevelt Roads Naval Station in eastern Puerto Rico. It sought to improve existing trapping techniques and to determine the effect cowbird removal has on the reproductive success of the endangered yellow-shouldered blackbird (Agelaius xanthomus). Decoy traps of two basic designs were used to capture 2449 cowbirds in 1162 trap-days (average 2.l/trap-day) in June-September 1985 and 850 cowbirds in 1571 trap-days (average 0.5/trap-day) in March-August 1986. The lower capture rate in 1986 suggests that cowbirds removed in 1985 were not being replaced during the non-trapping period. Trapping data from yellow-shouldered nesting areas in mangrove swamps indicated that cowbird capture rates were significantly higher (P=0.02) for large (14.2-14.8 m3) traps than for smaller (4.2 m3) ones. The effect of cowbird removal on the nesting success of the yellow-shouldered blackbird could not be directly determined because only one nest could be found. Cowbird removal, however, greatly reduced parasitism rates of another parasitized species, the yellow warbler (Dendroica petechia).

USING AIRCRAFT FOR CONTROLLING BLACKBIRD/SUNFLOWER DEPREDATIONS

Larry L. Handegard — Fri, 15 Jul 2005 07:51:27 PDT

Although not a new idea, using aircraft to control blackbird damage to sunflowers has provided some relief for sunflower growers in North Dakota. The numerous scaring devices and limited frightening agents have not proven effective in controlling blackbird damage to sunflowers. In response to a congressional directive to provide assistance in controlling blackbird/sunflower depredations in North Dakota, a blackbird hazing program was developed. The program utilized fixed-wing aircraft and shooting to expedite the migration of blackbirds through North Dakota.

PROLONGED SEED HANDLING TIME DETERS RED-WINGED BLACKBIRDS FEEDING ON RICE SEED

Dennis Daneke — Fri, 15 Jul 2005 07:48:19 PDT

Theoretical concepts from foraging ecology were studied to identify elements of blackbird foraging strategies that may be manipulated to deter blackbirds feeding on rice. Seed-handling time was identified as one such vulnerable element. Consequently, we developed seed coatings for rice that increased handling time per seed, allowed a satisfactory germination rate, and persisted for several days postplanting. Test coats included hydrophilic binders with several starches, clays, plaster of paris and chemical grout in various combinations. Consistent repellency was achieved in feeding trials with captive red-winged blackbirds.

BIRD DAMAGE TO SPROUTING RICE IN LOUISIANA: DYNAMICS OF THE MILLERS LAKE BLACKBIRD ROOST

Kristin E. Brugger — Fri, 15 Jul 2005 07:43:56 PDT

In spring 1986 and 1987 I examined the relationship between blackbird abundance and sequence of rice planting near a very large roost in southwestern Louisiana to identify factors that contributed to bird damage in newly planted rice fields. Millers Lake, an eutrophic man-made lake of approximately 2,500 ha, attracts a winter roosting population that peaks at 10 to 25 million blackbirds annually. By March and April the roost declines to several thousand birds. Female red-winged blackbirds (Agelaius phoeniceus) were responsible for most rice seed losses, predominating both the roost and feeding flocks in rice fields in spring. Number of flocking birds in fields decreased with roost size, date of year, and distance from the roost. Surveys corroborated recommended planting practices: planting after 24 March coincides with decreased numbers of blackbirds in rice fields, thus reducing the potential for damage to seeded rice by foraging blackbirds.