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| The FUNdamentals of Nest-finding "Spring's here!" The lilting whistle of the black-capped chickadee hangs in the April air as bird-watchers throughout the state sharpen their pencils and reach for their check-lists. Over the next few months, most birders will tick off the same suite of species as in previous years, while others will stumble upon the occasional rare breeder or storm-blown migrant. And then there are those who will go to extreme lengths, though not necessarily extreme distances, to locate a life bird. An increasingly popular and economical approach is to list first sightings from the bathroom window. Rest assured that there is a more dignified means of rekindling the sense of discovery. . . finding nests. By and large, the ability to locate bird nests is a learned skill requiring curiosity, serendipity, and patience. (Despite claims to the contrary, heredity is not a known factor.) When followed by regular and careful monitoring, nest-finding represents the single most informative research method in ornithology. By following these six tips, every reader can help solve the enduring riddles of avian ecology, including: What factors regulate reproductive success? and How vulnerable are bird populations?
Scope out potential nest sites before leaf-out impedes visibility. Scan tree crowns for bulky Crow's nests that could be re-used by hawks or owls. Look in barn rafters and beneath eaves and bridges for evidence of previous nestings by Eastern Phoebes, Barn Swallows or Cliff Swallows. Holes in eroded river bluffs will alert you to the possibility of a Bank Swallow colony or Belted Kingfisher burrow. Stick your head into hedgerows and see if Gray Catbirds, Northern Mockingbirds, or Northern Cardinals have nested there before. Search lowland thickets for the Yellow Warbler's neat cup or the Alder Flycatcher's messy one. Tree cavities provide nest sites for woodpeckers, Tree Swallows, Great-Crested Flycatchers, chickadees and nuthatches. Whether or not these off-season clues tip you off to the location of future nests, they will help you develop search images that will serve you well.
Study the breeding biology of the common birds in your area. Consult The Birder's Handbook (Ehrlich, Dobkin and Wheye, 1988) for information about nest location, size, shape, and material. Knowledge of the nest cycle is critical to interpreting the behaviors you observe in the field, so brush up on the timing and duration of the nest construction, egg-laying, incubation, and nestling phases. Also, be aware of how nest-building, incubation, and feeding responsibilities are divided between males and females. Whereas following a male Warbling Vireo during nest construction will yield pleasing results, tracking a male Scarlet Tanager in the same phase will waste your time.
The most informative cues are often the least obvious, so keep a sharp eye out for detail. When you frame a local breeder in your binoculars, focus first on the bill. If squirming larvae or a bundle of grass blades hang from it, the nest can't be far away. If it appears empty, look more closely for spider webbing, deer hair or other fine materials used in the nests of some species. Long flights across a territory typically precede deliveries of food or nesting material and can point to the nest's general location, or "nest patch." If you observe such a flight, do not disrupt the bird's behavior or go charging in on a hunch. Rather, watch patiently for repeated deliveries until you are confident of the nest's position. When approaching a nest, always step carefully, without lingering, and view it from as great a distance as possible.
Through evolution, birds have developed an impressive variety of tricks to cool their trails. Winter Wrens build dummy nests that are more obvious than their actual nests. Ovenbirds under observation may repeatedly pass through dummy nest patches when approaching their "ovens." In addition, many birds feign injury to lure predators away. Don't be fooled. Keep telling yourself that you are smarter than the bird; it may actually be true. Even the brightest beginning nest-finders have been duped by the "nest dance." This is a lively display in which an agitated adult hops vigorously perch to perch, giving a near-constant stream of alarm calls. If you observe the nest dance, you are close, but not close enough to make a find. Birds tend to be most secretive in the immediate vicinity of their nest and most agitated at the periphery of this core area. Back away until the agitation subsides and normal activity resumes. Continue to gather clues from a distance. If, by this time, you've become agitated by limited success and bountiful black flies, call it quits. Return the next day to the center of activity. Approach it from a new angle, staying ever alert for a bird flushing from its eggs.
Some birds exhibit highly stereotyped breeding behaviors. For example, female Dark-eyed Juncos have a unique call indicating nest departure. If you are able to recognize such "nesty" behaviors, your rate of discovery will rise considerably. The best way to develop superior acuity is to write down detailed descriptions of vocalizations and movements in your field notebook. By periodically sifting through these records, you can compile a list of the most revealing behaviors for each species. Furthermore, it is critically important that you monitor your nests according to the protocol established by the Vermont Nest-record Card Program. Participation in this program and adherence to its guidelines will ensure that your findings are useful and purposefully applied (see "Vermont Nest Card Program Takes Flight" Vol. 1 No. 1).
When properly performed, nest searches rarely influence avian productivity. However, excessive or intrusive study may contribute to nest failure. To minimize your impact, avoid: searching in foul weather, approaching a nest in the presence of a nest predator, trampling vegetation in a nest's vicinity, and distracting parents for more than a few minutes at a time. When monitoring a nest, walk past it instead of leaving a dead-end scent trail, use a stick to hold aside obscuring vegetation, and check out-of-reach nests with the aid of a pole-mounted mirror. Following these precautions can effectively nullify the risk of human-induced nest failure. By locating and faithfully monitoring nests this spring, you can make significant contributions to the understanding of Vermont bird life. Join the exceedingly sharp, the doggedly patient, and the unquenchably curious in embracing the nest-finding challenge. You will enter a new world of birding, where life-lists include a column for nests and watching the same old birds is exciting again. When should I fill out a card? What should I do if I find a rare or endangered bird? How many visits to a nest should I make? Nest-record Card (online form) 2001 Nest-record Program Report Download a nestcard (Microsoft Word document) | ||||||||||||||
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