Barbara Ballentine and Amber Keyser

Often, conservation efforts target human practices that are harming nature, but there are times when human activities can work hand in hand with nature. A recent AAES study has shown that a few minor alterations to traditional agricultural practices can drastically improve bird habitat, which can benefit farmers and birds alike.

The study, which was initiated three years ago, focuses on breeding birds in an agricultural landscape. Many of the bird species that breed in the southeastern United States (see the table) are migrants that winter in Central and South America. Recently, conservation efforts on the wintering grounds of these birds have focused on cooperative ventures between coffee farmers and biologists. Shade-grown coffee farming techniques leave large hedgerows of native trees to provide shade to coffee plants. This practice involves leaving entire tracts of forest around the perimeter of coffee plant fields. The forest canopy provides shade to the coffee plants, and this farming technique produces a choicer grade of coffee, which fetches a higher price on the international market. In addition, these trees provide crucial habitat to wintering birds. However, this is only half of the solution. The birds need to be protected on both the wintering and breeding grounds, closing this conservation gap.

Birds Breeding on Agricultural Lands In Lee County, Alabama

Common name Scientific name Killdeer Charadrius vociferus Wild turkey Meleagris gallopavo Common bobwhite Colinus virginianus Mississippi kite Ictinia mississippiensis Red-tailed hawk Bueto jamaicensis Red-shouldered hawk Bueto lineatus Broad-winged hawk Bueto platypterus Turkey vulture Cathartes aura Black vulture Coragyps atratus Eastern screech owl Otus asio Barred owl Strix varia Common barn owl Tyto alba Common ground dove Zenaida macroura Mourning dove Columbina passerina Yellow-billed cuckoo Coccyzus americanus Chuck-will's-widow Caprimulgus carolinensis Common nighthawk Chordeiles minor Ruby-throated hummingbird Archilochus colubris Chimney swift Chaetura pelagica Belted kingfisher Mageceryle alcyon Pileated woodpecker Dryocopus pileatus Common flicker Colaptes auratus Red-bellied woodpecker Melanerpes carolinus Red-headed woodpecker Melanerpes erythrocephalus Downy woodpecker Picoides pubescens Hairy woodpecker Picoides villosus Eastern wood pewee Contopus virens Acadian flycatcher Empidonax virescens Great-crested flycatcher Myiarchus crinitus Eastern phoebe Sayornis phoebe Eastern kingbird Tyrannus tyrannus Barn swallow Hirundo rustica Purple martin Progne subis American crow Corvus brachyrhynchos Blue jay Cyanocitta cristata Tufted titmouse Parus bicolor

Common name Scientific name Carolina chickadee Parus carolinensis Brown-headed nuthatch Sitta pusilla Carolina wren Thryothorus ludovicianus Blue-gray gnatcatcher Polioptila caerulea Northern mockingbird Mimus polyglottos Brown thrasher Toxostoma rufum Eastern bluebird Sialia sialis Wood thrush Catharus mustelinus Loggerhead strike Lanius ludovicianus Yellow-throated vireo Vireo flavifrons White-eyed vireo Vireo griseus Red-eyed vireo Vireo olivaceus Northern parula Parula americana Prairie warbler Dendroica discolor Pine warbler Dendroica pinus Swainson's warbler Limnothylpis swansonii Common yellowthroat Geothlypis trichas Kentucky warbler Oporornis formosus Ovenbird Seiurus aurocapillus Louisiana waterthrush Seiurus aurocapillus Hooded warbler Wilsonia citrina Yellow-breasted chat Icteria virens Orchard oriole Icterus spurius Brown-headed cowbird Molothrus ater Common grackle Quiscalus quiscula Eastern meadowlark Sturnella magna Summer tanager Piranga rubra Northern cardinal Cardinalis cardinalis Blue grosbeak Guiraca caerulea Indigo bunting Passerina cyanea House finch Carpodacus mexicanus Grasshopper sparrow Ammodramus savannarum Rufous-sided towhee Pipilo erythrophthalmus Field sparrow Spizella pusilla

Many neotropical migrant songbirds breed in temperate agricultural areas, and farmers in North America are an important part of any conservation agenda. Each species of bird has specific habitat requirements. Some are extremely specific; for example, black-and-white warblers will only breed in mature hardwood forests. Others, such as northern mockingbirds, will breed in suburban backyards. However, all birds share the same basic requirements for successful breeding: plenty of places to build nests, nest sites that are safe from predators, and foraging areas.

Migration is the first hurdle breeding birds face, but even birds that successfully arrive at the breeding ground face numerous difficulties. While some predators do take adult birds, the first few weeks are the most dangerous period in a bird’s life. Only a small percentage of eggs survive to hatching, and of these, only a few nestlings make it to the fledging stage (the stage in a bird's life shortly after it leaves the nest when it is still dependent on adults for food).

Dangers to eggs and nestlings are numerous: crows, blue jays, snakes, squirrels, opossums, raccoons, chipmunks, and rats. Brown-headed cowbirds pose a different type of threat because they lay their eggs in the nests of other birds, and the cowbird nestlings often out-compete other nestlings for food provided by the host parents.

Blue grosbeak nest with eggs.

Northern cardinal nestlings.

Brown thrasher.

Despite these many natural problems, birds do manage to breed successfully. However, feral cats and dogs can increase the predation pressures on nesting birds and can mean zero success for birds trying to breed in areas close to humans. As a result of these pressures and the absence of suitable habitat, very few species can successfully breed in close proximity to humans. Therefore, research has focused on utilizing rural agricultural lands where few people reside.

The study has shown that several farming practices can be used to protect breeding bird populations. The most important thing farmers can do to increase the breeding success of birds in their fields is leave ample hedgerows around fields. The small trees and shrubs that grow along field edges and fence rows provide foraging areas, nest sites, and shelter from predators.

Birds often forage on grass and weed seed that is available in grassy strips that often grow between forested areas and fields, especially when they have just returned from the long migration. When field edges and hedgerows are sprayed with herbicide in an effort to “clean-up” around the field, these areas become unusable and birds are displaced. Obviously, vegetation in these areas needs to be partially controlled so it doesn't encroach into crop land, and often farmers mow these areas during the summer.

Invariably active bird nests are destroyed during mowing. If farmers can wait until the end of the summer to mow, the majority of birds will have finished breeding. Some minor adjustments in field maintenance can mean the difference between success and failure for nesting birds and would be inconsequential to the farmer.

Male brown-headed nuthatch.

Female black-and-white warbler.

Male eastern bluebird on box.

Fallow fields also fulfill many habitat requirements for both breeding and wintering birds. Grassy fields provide food and cover to a wide variety of birds, including many common game birds such as wild turkeys, bobwhite quail, and mourning doves. Since agricultural research has shown that leaving fields fallow also replenishes nutrients lost to agricultural crops, retains moisture, and prevents soil loss to erosion, farmers may want to consider rotating fallow fields among crop fields to benefit both their production and the birds that reside around the fields.

Pesticide application is necessary for crop production, but it can be harmful to breeding birds. However, there are several ways farmers can reduce this threat. Localized, directed pesticide application reduces the exposure to birds using field edges and hedgerows. In addition, carefully controlled application reduces costs. When possible, application should be timed to avoid periods of peak nesting activities, which typically occur between May and August. Farmers can also consider birds their allies in pest management because they provide free pest control services by feeding huge quantities of insects to their voracious young.

Many farmers manage the land surrounding their fields for timber. Mature stands of forest are good for some bird species, such as thrushes, vireos, and warblers, and areas that are harvested for timber are productive for other birds, such as bluebirds, woodpeckers, nuthatches, titmice, and chickadees. These birds are cavity-nesters and use large, dead snags left after timber harvest for nesting sites. As cut areas begin to regrow, new saplings provide nest sites for many cup-nesting species, like grosbeaks and chats. A well-thought-out forest management plan can be financially lucrative for farmers and does not necessarily mean disaster for the birds.

Farmers also can help birds by allowing biologists access to their land for bird research. The more knowledge that is gained, the more effectively these animals can be protected and conserved. Conservation efforts do not have to be a burden for farmers. Rather, by working together and avoiding the antagonism that often characterizes conservation issues, good biology can dovetail with farming practices in a way that is mutually beneficial.