It’s nesting season again. For something so basic and so essential to avian life, I believe that the act of nesting, why there are different kinds of nests and other general details are vastly miss-understood by many. Let’s go over some very basic stuff and try and clear up a few things about nesting.
First, avian nesting is fairly unique to birds and is only loosely related to mammals denning or people and their homes. For the vast majority of birds a nest is a temporary structure that is used just once and as soon as the babies leave the nest, which is called fledging, they don’t return or use the nest again.
There are many different kinds of nests. Each species constructs a nest that is unique to their species. For example the Black-capped Chickadee will always construct a nest made of green moss inside a small cavity. They may excavate a cavity on their own in a tree or they may use an existing cavity, but they will always be in some kind of cavity and they will also have a nest consisting of green moss.
A simple cup nest is used by three-quarters of all songbirds. This is a simple structure that is obviously cup shaped and is exposed to the world around them. These nests are constructed from the bottom up. First a platform is attached firmly to a tree or other structure. In the case of American Robins mud is the glue to adhere the nest to the tree. Others will just tightly weave the bottom platform to the branches. Next the sides are added then last the inner cup or lining is added. A few birds that use these kinds of nests are robins, blue jays, red-winged blackbirds, cardinals and other familiar birds. It is important to know that these nests are used once and never again by the owner/builder. However as always in nature there are some exception to this rule but it is not very common.
Hummingbirds construct amazing cup nests. It is a tiny nest, slightly larger than a half of a walnut, and is made with very fine plant materials and glued together and attached to a branch with spider webs. The design of this nest allows for the nest to expand as the family grows. The nest starts out only large enough to just fit the female but later must accommodate two babies as they grow. This is amazing planning for fore-thought.
Primary cavity nesting birds are a group of birds that consists mainly of the woodpeckers. They are called primary cavity nesting birds because they are the builders or more accurately described as the excavators of these homes. Woodpeckers use their long pointed bills to chisel a small cavity into what is usually dead wood of a tree. It often takes upwards of a week to dig out these nests. Very labor intensive prospects but the payoff is well worth it. Cavity nesting birds have a higher rate of baby bird survival than open cup nesting birds. The cavity not only protects the occupants from predators but it is also warmer and definitely dryer.
For most species of woodpecker these cavities are used only once and as soon as the young leave the cavity they never return. In most species of woodpecker the cavity is not used like a year round home with the exception of the Red-headed Woodpecker and the Red-cockaded Woodpecker. These birds return to the same cavity each night. This is seen as very unusual behavior.
A huge benefit of these woodpecker homes are the cavities from last year are available for other, non cavity excavators to use. For example a very unusual cavity nesting bird is the Prothonotary Warbler. While most other species of warbler nest in open cup nests, the Prothonotary takes advantage of the left-over cavities to set up shop and raise their young. This gives them great advantages over other warbler species.
Some birds such as Prairie Falcons don’t build a nest at all. They lay their eggs on flat spot on some rocky cliff. Great Horned Owls also don’t build a nest but instead take over an old hawk or crow nest. Some owl species nest in cavities while others nest on the ground.
Over all nesting birds are another example of how amazing mother nature can be. Very complex but yet very basic and simple. Until next time…
Stan Tekiela is an author / naturalist and wildlife photographer who travels the US to study and photograph wildlife. He can be followed on facebook.com and twitter.com and can be contacted via his web page at www.naturesmart.com