Now more than ever, we need your support. Make a donation to the Smithsonian's National Zoo and Conservation Biology Institute today!
Nest Monitoring Guidelines
Following the life of a nest provides the opportunity to make an important scientific contribution but must be done very carefully. The guiding principle to responsible nest monitoring is conducting observations with as little disturbance as possible.
What is Nest Monitoring?
Nest monitoring tracks all or part of a bird’s nesting attempt, including the building, laying, incubating, nestling and fledgling stages. Several kinds of data are recorded, including dates and numbers of eggs, nestlings and fledglings.
Monitoring can begin at any stage during a bird's nest attempt. Preferably, data for at least three visit dates should be recorded, including the final visit to determine whether the nest was successful (the nest fate). Monitoring nests through this final stage is preferred, because it is the only way to know if reproduction was successful, but data is useful and should still be submitted even if there are fewer than three visits and/or if the final success or failure date is missed.
A nest is considered successful if it produces at least one young, or fledgling, of the same species. The Nest Data Form outlines the activities involved in monitoring a nest and provides a place to record your observations, along with the Nest Monitoring Calendar. How much monitoring is required will depend on when the nest was found within its cycle and whether the nest fails.
Timing of the Nesting Season and Nest Monitoring
Because Neighborhood Nestwatch includes several geographic regions, the nesting season can begin at different times of the year. In general, year-round resident birds, such as chickadees, Carolina wrens and cardinals, begin nesting around mid-March in the southeast and about a month later in the northeast. Long-distance migratory birds, such as house wrens and gray catbirds, begin nesting about one month later for each respective region (mid-April in the southeast and mid-May in the northeast).
Keep in mind that many birds will attempt more than one nest per breeding season, particularly if earlier nest attempts fail. Any nest attempt can be monitored.
Generally, nests are built within two to three days. Eggs are then laid at a rate of one egg per day. The day before the last egg is laid, most songbirds begin incubating the eggs. Incubation typically lasts 11-14 days, and most songbird eggs hatch within 24-48 hours of each other. Depending on the species, nestlings need 10-18 days to sufficiently develop before they can fledge, or develop the wing feathers required for flight.
The Nest Cycle Guide outlines the duration of incubation and nestling periods for focal species, to assist with recording accurate dates.
Nest Monitoring FAQs
Before getting started, carefully review these FAQs. If you will be away for an extended period of time while monitoring a nest, ask a friend for help or contact us.
What birds can I monitor?
How many times should I observe a nest?
You should make at least three observations per nest, including the final observation to determine the nest fate (whether the nest was successful).
How often should I visit a nest?
The building and incubation stages are the most sensitive periods of the nest cycle. When birds are building, avoid the area immediately surrounding the nest. During incubation, visit the nest every three days. During the nestling stage, plan to visit the nest every two days.
How close will I need to be to the nest?
Some questions can be answered far from the nest. Is the nest still being built? Is it still active? Have the eggs hatched (i.e., are adults carrying food to nestlings)? But most data relies on quick and careful nest visits at close range.
What if I miss a day of nest monitoring?
How do I know if a nest was successful?
A nest is considered successful if it results in at least one fledgling, or young bird, of the same species.
How can I continue to monitor a nest during the building and incubation stages without disturbing the birds?
Nests should be avoided during nest building and the first few days of incubation. Use binoculars from a distance, or check the nest when adults are not present, such as when the female occasionally leaves the nest to feed.
What is the best time of day to check a nest?
Check nests in the afternoon. Do not check nests in the early morning, because most females lay their eggs in the morning. Eggs or young nestlings can also quickly become cold if left alone in the morning. Also avoid checking nests at or after dusk, because females may be returning to the nest for the night.
Can I touch a nest that I am monitoring?
No, avoid touching nests, eggs and young.
Can I approach a nest when young are close to fledging?
No, do not approach nests when young are close to fledging (leaving the nest). Despite being quite mobile inside a nest, nestlings still may have to undergo significant development before being able to fledge. If young birds are disturbed during this stage, they may leave the nest prematurely unable to fly. Birds that fledge prematurely do not usually stay in the nest despite attempts to return them, which leaves them with little chance of surviving. Once the young birds are fully feathered, you can check the nest from a distance with binoculars to determine if the parents are still actively feeding the young.
How does the weather affect nest monitoring?
Avoid nests during bad weather, because checking nests during this time can be very stressful for birds. If the weather is cold, damp or rainy, postpone checking the nest.
Should I record my observations while at the nest?
No, you should wait until you are at least about 30 feet (10 meters) from the nest before stopping to record data.
What should I do if I see a potential nest predator?
Be wary of nest predators, and do not approach a nest if you see one. Be sure dogs, cats, crows or jays are not following or watching you. Nest predators are everywhere.
Is it OK to take the same route to and from a nest?
Whenever possible, take a different route away from the nest site than the route you took to reach it. This will help you avoid leaving a dead-end trail to the nest. Walking a back-and-forth route leaves scent trails that predators can use to later find and disturb the nest.
How should I approach a nest?
Minimize disturbance and do not startle the parents as you approach, as this may cause eggs or young to be knocked out of the nest. The best time to quickly check a nest is when parents are absent. Wait a few minutes to see if adults leave the nest on their own before approaching. Sometimes, a short wait is all it takes.
How do I observe a nest that is inside a nest box or out of reach?
Nest boxes should be lightly tapped first to allow the parent to slip away before you stare directly into the box. Use small mirrors attached to poles for nests that are out of reach.
What is brood parasitism, and how can I recognize it?
Brood parasites rely on other birds to raise their young. Brown-headed cowbirds, a species common to all Nestwatch regions, lay their eggs in the nests of other birds. Those birds, called host species, then raise cowbird chicks as their own—often at the expense of the host's own offspring. Be mindful of the number of cowbird eggs or young you see when monitoring a nest. Cowbird young develop very quickly and usually crowd the host young.