Nesting Season

a time of new beginnings

Nesting season begins in February and depending upon the specie may last through mid-summer, although there are a few exceptions, like the barn swallows who return to San Miguel in late spring and nest all through the summer.

This is a very special time of year, the beginning of a new generation of birds living amongst us.  Those who regularly watch birds will likely notice behavorial changes, which provide clues to where a nest is being made or located.  We can then watch and listen for nestlings and fledglings, always keeping a safe distance in order to not disturb. If you know where to look (information below), it helps you to become more observant on walks or while in your garden.

Trimming trees or shrubs should be avoided during this season, unless you have methodically searched for nests.

If you are interested in serious nest watching, and would like to contribute nest monitoring information to science, visit the Cornell Lab of Ornithology Nest Watch website.

Nestwatch.org

An Introduction to Bird Nests

Nest building: 

Most birds make their nests in trees or shrubs, but some species make nests on the ground (like the Long-billed Dowitcher and American White Pelican) or use a hole or crevice in rocky cliff (such as the Canyon Wren), while other birds (like the Bronzed and Brown-headed Cowbird) lay theirs eggs in the nests of other birds, letting unsuspecting “foster parents” do all the work of rearing the young.

In most species, the female does most or all of the nest construction, though the male often helps, however there are species where the male does most or all of the nest building, such as members of the egret family.  Juveniles may also act as helpers for the adults.

The skill to build a nest is instinctive; some birds raised in captivity can build nests typical of their species without ever having seen one.   However, researchers found that young birds do improve their nest building skills with practice; changing their technique from one nest to the nest and becoming more proficient in handling materials.

Nest design:

For a long time it was thought that nest design was primarily a function of security, but recent research reveals that nests are multifunctional –  influencing partner selection, minimizing parasites, and creating microclimates in reaction to environmental conditions.

Each layer of a nest serves a specific purpose.  Generally, coarse twigs often form the base while finer twigs and weeds are laced with bark to create the cup.  Dry leaves, fine grasses, and other soft materials form the inner lining.  Most birds build a new nest each year, though some refurbish their old nests and some occupy former nests of a different species.

There is often considerable variation in a nest of a particular species, depending on the individual, circumstances, location and available materials.

Nest designs common to the birds of SMA

Cup: The cup is the most common type of nest – smoothly round inside, with a deep depression to hold the eggs. Most are made of flexible materials, though a small number are made of  mud or saliva. The Vermilion Flycatcher, hummingbirds, and Barn Swallows are just a few local examples of birds that make cup nests.

Scrape: The simplest nest construction is the scrape, which is  a shallow depression in soil or vegetation and typically has a rim deep enough to keep the eggs from rolling away.  Sometimes the scrape is lined with vegetation, small stones, shell fragments and feathers.  Spotted Sandpipers and American White Pelicans build a scrape nest.

Pendant:  Woven pouches that hang from the limbs of trees, using the fibers of nearby plants to create the structure.  Often lined with hair, softer plant fibers, wool and mosses.  Orioles build pendant shaped nests.

Saucer or plate:  The saucer or plate nest, though similar to a cup nest, has only a shallow depression to house the eggs.  American Coot and Least and Pied-billed Grebes build saucer shaped nests.

Platform: The platform nest is a large structure, often many times the size of the (typically large) bird which has built it. Depending on the species, these nests can be on the ground or elevated.  Great, Snowy and Cattle Egrets, Blue, Green and Black-Crowned Night Herons, Osprey and Crested Caracara are a few examples of local platform nest builders.

Cavity: The cavity nest is a  hole typically located in living or dead wood, but sometimes in the trunks of tree ferns or large cacti, including organos.  Woodpeckers and Kestrels are examples of local cavity nesters.

What to look for and where to look

A sampling of local bird nest  and nesting information, plus tips on where to look!

Sources:  All About Birds and Nest Watch, Cornell Lab of Ornithology; National Audubon Society; Scientific American Magazine; US National Library of Medicine; University of Edinburgh; Utah Birds, CONABIO, Naturalista, Nest Watch.