Once you have located a nest, follow these steps:
If you do not know what species the nest belongs to, you can use field guides to help identify the parents and you can also get clues from the nest. If you're still uncertain, send us a photograph of the bird and/or nest and we can help you identify the species. Please only submit data on nests for which you can confidently identify the species.
Choose a reference point near the nest (but at least 10 m away) that will be easy to locate and remember (e.g., a large tree, shed, gate, etc.). Make a sketch in your field notebook from the reference point noting the distance and direction to the nest. You'll also want to approximate the height of the nest and note what type of tree, shrub, or other substrate it is in.
Never put flagging tape or any marking material close to a nest. This could attract predators. If you do need to mark a nest in the field, place a small piece of flagging tape at least 5-10 m away and record the location of the nest from the flagging tape in your field notebook or on your data sheet. Make sure to take detailed notes on nest location; it can sometimes be challenging to re-locate nests as they become more hidden by foliage later in the season.
Visits throughout the entire nesting attempt are very useful because each period provides different information (e.g., clutch size, brood size, nest outcome, etc.). If you cannot check the nest every 3-5 days, try to check it two or more times with visits spaced about a week apart. If you only visit a nest once, please still enter the data. Single nest visits can contribute valuable information to the distribution or nesting chronology of a species.
Note that you should not check a nest more often than every 3-5 days, to minimize disturbance to nesting birds.
Sometimes there are unhatched eggs or dead young left in a nest after it has fledged. It is important to try to gather this information by checking the nest after the young have left.
Nests are often a few metres above ground, making it challenging to check the contents without special equipment.
Note that if you are using equipment to check a nest, such as a mirror on a pole or a stepladder, it is often helpful for ease of data recording and for safety, to have another person assist with the nest check.
Nest boxes should be designed so that one of the panels can be opened to check nest contents. Before opening the panel or looking through the opening, give a few gentle taps on the box, so the adult can exit. This reduces the risk that the bird will damage the eggs or crush the young upon leaving. Eastern Bluebird and Tree Swallow nest boxes on roadsides or public property are often monitored by dedicated volunteers. Before checking any nest boxes that do not belong to you, make sure you get permission from the owner.
Monitoring nesting activity allows us to gather important information about where and when breeding occurs, and how successfully birds are producing young. This information can help determine the health of bird populations, and highlight changes that may be occurring in the nesting success, breeding biology, or distribution of a species.
When you are monitoring a nest, there are several important pieces of data that you are trying to collect including:
Although it may be difficult to gather all of the above information for each nest, data gathered from multiple nests and observers helps tell the full nesting story for a species and track changes over time.
|Nest monitoring - key terms|
|Clutch size||The number of eggs a female lays in a single nesting attempt|
|Brood size||The number of birds hatched from a single clutch of eggs|
|Altricial young||Birds that are naked, blind, and helpless when they hatch (e.g., most songbirds)|
|Precocial young||Birds that are fully feathered, mobile, and active when they hatch (e.g., ducks, geese, shorebirds)|
|Incubation period||The length of time the clutch is incubated|
|Hatch date||The day the young hatch (may occur over a couple of days)|
|Nestling period||The length of time the young remain in the nest|
|Fledge date||The day the young leave the nest (may occur over a couple of days)|
Brown-headed Cowbirds do not build nests or raise young. Instead, they lay eggs in other birds' nests. Cowbird young are then raised by other species, often to the detriment of the species' own young. The Brown-headed Cowbird is the most common parasitic bird species in North America and has been found to lay its eggs in nests of more than 200 species. If you find a Brown-headed Cowbird egg in a nest, please do not remove it. Continue to monitor the parasitized nest to determine the fate of the host eggs as well as the Brown-headed Cowbird egg(s).