A great time to look for birds nests is after birds migrate in the fall. You can easily see nests which were hidden by leaves all summer. Finding, examining and identifying nests can add to your knowledge of birds and add to your enjoyment of the hobby.
If you are an avid birdwatcher, you already know where many nests can be found. I knew of Barn Swallow nests up under my porch, and also that Cardinals had built a nest in my Red Bud tree and another in the Water Oak. I knew there were bluebirds in a nesting box and that mockingbirds, robins, and wrens had nests in my yard. I was delighted to spy an oriole's nest hanging from the Red Oak's outer branches high above the ground.
Nests from bird houses
It's time to clean out the bluebird house. I learned that if I don't clear out the used nests, the birds will build next spring's nest on top of the old one, which places the eggs and chicks in easy reach of marauders, like snakes and woodpeckers.
Martin houses and new bird houses should be hung in the fall to give them time to air and rid themselves of human scents. Bluebirds locate a house in the early winter but don't build in it until they return to the area in the spring.
Many folks plug the openings of their birdhouses to keep out mice and other critters who might lodge there. If you do this, be careful to watch for the return of the birds and have the houses open.
Some nests are dislodged by autumn and winter winds. Look for nests in low branches, shrubbery and fence rows. It is okay to take a bird nest since the birds only use the nests to raise their chicks and the next year they rebuild. Studying nests can help you become a better birdwatcher.
What bird built it?
A careful examination of nests can tell you what bird nested there. Each species builds a certain style of nest with similar materials. The location, shape, size and construction of the nest tells me what species it belonged to. With this information, I can surmise what sorts of nesting materials to put out for the birds I want to watch.
The Peterson Field Guides to Birds' Nests (Eastern and Western) by Hal H. Harrison are the most fascinating sources for this information. The nests will be found in predictable spots and areas; i.e. fields, wooded areas, near houses, along stream beds, in barns and derelict buildings, on the ground and in certain bushes or trees, and built at a certain distance from the ground or water.
Examine the nest to see what materials it was constructed of. Look for horse hair, rabbit fur, wool and other mammal furs from shedding animals, feathers, milkweed fibers, thistle and cattail down, lichen, hay, clover, weeds, snake skins, human hair, bits of cloth, pine needles and leaves. Materials may include grasses, twigs, rootlets, mud, reeds, vegetation of many sorts, moss, saw dust and shredded bark.
I have found shreds of plastic grocery bags, string, yarn, strands of white cotton fibers (that look suspiciously as if they'd been stolen from my kitchen floor mop), plastic pop-can connectors, ribbons, bits of unidentifiable plastic and fishing line. Many of the items are dangerous man-made litter that can harm birds. Keeping your area clean of litter and keeping lids on trash cans can save birds from these hazards.
North American bird species
Some of the nests you are most likely to spot, besides nesting-box nests, are the nests of catbirds, orioles, cardinals, mockingbirds, robins, thrushes, veerys, kinglets, Cedar Waxwings, Loggerhead Shrikes, warblers, vireos, and Red-Winged Blackbirds.
Studying found nests helps me know what birds are nesting on my property so I can be a better bird hostess, and choose the best type of houses, feeders and bird foods for the coming year.
Studying bird nests each fall, making notes of the placement and style of each nest, has certainly convinced me how much more there is to know about the winged wonders of our world.