Stop! Look! And Listen!
The red rim of the rising sun was barely visible on the eastern horizon as I took the Williamsburg exit off Interstate 70. It was June, 2002 and I was on my way to conduct the annual survey of breeding birds on the Whetstone Creek Conservation Area.
When the surveys began in 1977, the Missouri Department of Conservation had only recently acquired the Whetstone Conservation Area, and I was a newly hired research biologist. Now, I was about to participate in my 25th annual breeding bird survey on the area. As I turned off the blacktop and onto the gravel road that leads into the area, I couldn't help but reflect on the changes that the Whetstone landscape and its bird community had experienced during the last 25 years.
When the Conservation Department bought Whetstone, it was a working cattle ranch. Covering more than 5,000 acres, it was half open land and half forest. The broad ridges had been planted to cool-season pasture, in which the predominant grass was fescue. The valley of Whetstone Creek, from which the area would derive its new name, was fescue pasture, as well. Grazing on these pastures kept the vegetation clipped so low that it was possible to stand on one side of a large pasture and see up to a mile across it to the other side. The draws leading down from the uplands to the valley were forested, and much of the woodland was grazed. There were some crop fields in the southwest and northwest corners, but they represented only a fraction of the overall area.
Several different Conservation Department managers have had a hand in shaping the landscape of the Whetstone Area since 1977. Early on, they battled to convert the vegetation from big expanses of fescue to smaller, more diverse patches of cover and food for wildlife. Native grasses have been planted to replace some of the fescue, which is a non-native grass. Today's management of the area employs a number of practices, including controlled burning, grazing, haying and grain planting in the open lands; and timber cutting and thinning in the forest lands.
Creating wildlife habitat has been the goal of management since the beginning. Some people first think of the animals that provide hunting opportunity when they think of wildlife, which isn't surprising. They like to see deer when they drive around Conservation Department land in the summer or winter, and they like to have a place to hunt turkeys in the spring or quail in the fall. These are important considerations and have been an integral part of managing the Whetstone Area since its acquisition.
However, the Conservation Department is responsible for all wildlife, including songbirds. These are among the most visible, the most vocal, and, for many people, the most enjoyable species of wildlife.
Different birds live in different habitats. Therefore, we use a variety of land management practices to create an array of habitat to benefit many bird species. These range from the open, low habitat of crop fields and grazed pasture to old fields to the multiple layers that exist in a mature woodland. If suitable habitat for a particular type of bird is present, usually that bird is present. As the habitat changes, so, too, does the composition and abundance of the bird community. The breeding bird survey is one of the tools we use to monitor the composition of Whetstone's bird community.
This is how the breeding bird survey works: Using a car or truck, I drive the roads that wind through the Whetstone Area. Every half mile I stop, turn off the engine, get out and listen for bird calls and look for birds for three minutes. I record each bird I see or hear on a clipboard and paper. There are 25 stops on the route, and it takes about three hours to run it.
This method is effective because the birds are breeding in the early summer, which means that many of them advertise their presence by singing loudly. I stop at the same places every year, making it possible to compare survey results from each stop year to year. It is especially interesting to look at long-term trends, to see which bird species were there in 1977, which have moved out, which have moved in, and which bird species are still present in 2003.
In the first few years of the survey, grassland birds were abundant on the Whetstone Area. I recorded high numbers of eastern meadowlarks, dickcissels, and grasshopper sparrows. Meadowlarks remained abundant through the 1980s, but their numbers began declining in the 1990s. There are still a few on Whetstone, but not many. Dickcissel numbers have also declined.
Grasshopper sparrows were numerous when cattle grazed the grass low to the ground. As the grass grew dense with no herbivore to chomp it back, grasshopper sparrow numbers dropped to near zero by 1981. Only occasionally does one show up on the survey.
An interesting story is that of the Henslow's sparrow, a prairie bird. Henslow's sparrows prefer tall, thick grass and nest in dense, dead stems in the hearts of grass clumps. There were no Henslow's sparrows on Whetstone the first year of the survey. By 1978, the grass on the area was tall and had a thick thatch of residual stems from the prior growing season. A few Henslow's sparrows showed up that year. The population peaked in 1979 and then trailed off. A few have shown up in the intervening years, but some years there are none. Today, I may detect one or two on the survey.
Bobwhite quail and mourning doves live in both grassland- and cropland dominated landscapes. Both of these game birds have been common breeding birds on Whetstone throughout the period of the surveys, but their trends have moved in opposite directions. Mourning dove numbers have declined, but the bobwhite is more abundant.
Although usually regarded as a marsh or wetland bird, the redwinged blackbird has consistently been the most common bird in the Whetstone Area breeding bird survey. Redwings are found at the area's many ponds and lakes, but they are highly adaptable and will nest in a wide variety of habitats, including dense grasses, roadsides, and field edges. Red-winged blackbirds have been recorded every year, and in most years it has been the most plentiful species detected.
As former pastureland and cropland was broken up into smaller units in the late 1970s and 1980s, fencerows and field borders were planted or allowed to grow into woody, shrubby hedgerows. Gray catbirds, common yellowthroats, yellow-breasted chats, cardinals, indigo buntings, rufous-sided towhees, and field sparrows all live in this habitat. All of these species were present on Whetstone when the surveys began, but their numbers rose in the 1980s, and they are still common on the area today.
The Bell's vireo is a shrub nesting species. Managers are interested in it because its population has been declining in parts of its range. In 1980, the first Bell's vireo was detected on the Whetstone survey. The species has been present in low numbers every year since 1983.
The song sparrow, another shrub nester, did not show up on the survey until 1997, but is now a regular fixture.
Trees in the Whetstone Area woodlands have matured in the last 25 years, but the amount of forested acreage has stayed more or less the same. Likewise, the composition of the forest-dwelling songbird community has not changed appreciably throughout this period. The numbers of the forest birds haven't changed much, either. Some common species in the Whetstone woodlands are yellow-billed cuckoo, eastern wood-pewee, blue-gray gnatcatcher, summer tanager, rose-breasted grosbeak, great crested flycatcher, and Kentucky warbler.
Despite its success, the breeding bird survey technique has several limitations. The primary drawback is that the survey is conducted along roads. Roads, of course, mostly go through uplands. Consequently, not all of the habitats on an area are proportionally represented in the survey. At the Whetstone Area, the riparian zone along the creek is represented by only one stop in the survey, and the woodlands are represented by only seven or eight stops.
Generally, birds must be singing to be detected, so the survey does not account for species that have already finished nesting, species that do not vocalize or those whose calls do not carry very far. Since it is a daytime survey, it also does not pick up nocturnal species. For these reasons, this technique should not be the sole measure of questions regarding bird populations, nor should it be the sole means to measure the response of a particular species to a management practice on the Whetstone Area.
In all, 95 species of birds have been recorded on the Whetstone Area breeding bird survey over these 25 years. I looked back over the data to see what to expect in the course of a morning survey. The average number of species that was detected in a morning was 49. The highest was 58 species, and the lowest was 43 species. The average number of individual birds detected in a morning was 404, with a range of 263 birds to 806 birds.
To me, these figures are more than mere numbers. They show that the composition of the bird community has changed as the habitat changed. I hope to continue to conduct the Whetstone Creek bird survey. It's a great excuse to get up early and listen to the chorus of bird songs on a June morning.
Birding on Conservation Areas
Conservation areas throughout the state provide countless opportunities for avid and casual birdwatching. For example, waterfowl viewing is spectacular in February and March at Eagle Bluffs Conservation Area in Boone County. During summer, look for Swainson's, hooded and prothonotary warblers in the forests along Ozark rivers. Numerous conservation areas provide access to these streams.
From July through October you can find thousands of shorebirds and herons foraging on the muddy flats of drying up wetlands at Grand Pass (Saline County), Otter Slough (Stoddard County) and Shell-Osage (Vernon County) conservation areas.
An informative publication, A Guide to Birding in Missouri, published by the Audubon Society of Missouri, describes 112 birding hot spots in the state, including 44 conservation areas. You can purchase the book at Conservation Department offices, or on-line by going to www.mdcnatureshop.com. -- Brad Jacobs