Understanding NestWatch Data

NestWatch Data Relationships
NestWatch Data Collection

This is the order in which the data are collected

Nest Site

This is the physical location of the nest. A nest site can have multiple attempts and can be a cup nest, a nest box, or a nest structure. You will be asked to describe the nest and its general vicinity.

Data Collected At This Level: Location (latitude and longitude), Substrate (where it is attached), Habitat, Height above ground, Elevation above sea level

Nesting Attempt

This is generally a multi-day event by a pair to produce young. An attempt spans from the first egg laid to various endpoints, usually (but not always) leaving the nest at a zero state (no eggs, no young).

These endpoints can include:

  • All young birds left the nest (fledged)
  • All the eggs or young consumed by a predator
  • Eggs failed to hatch and were removed by the participant
  • A nest was taken over by another species

Whenever a nest reaches an endpoint (whether successful or failed) a nesting attempt should be summarized and ended.

Data Collected At This Level: Species, Predator guard type (for nest boxes), Whether or not you provide supplemental food, and when (for bluebirds and chickadees only)


This is a single event when you collect data about your nesting attempt at your nest site. Visits should be about every 3 to 4 days.

Zero Means a Lot!

When entering visit data, it is important to know the difference between entering a zero, marking a nest unknown, and leaving a field blank.

Leaving a field blank and marking a nest unknown (“u”) are not the same. Scientists will not be able to use blank fields (unanswered) in analysis, but “u” signifies that eggs or young were present but uncountable.

Entering a zero explicitly shows that you looked for this data point and the count number is zero. It is very important to enter zeros as this will help analysis tremendously!

Data Collected At This Level: Date and time of visit; Number of eggs, hatched young, and dead young; Status and activity codes; Presence of cowbird eggs or young; Observer initials; Additional notes

Nesting Attempt Summary

When a nest attempt reaches an endpoint (either successful or failed), you should end that nest attempt and tell us the final outcome. You’ll be asked to summarize things like first egg date and first fledge date which we may not be able to surmise from the visits.

Data Collected At This Level: First egg laid date, hatch date, and fledge date, and whether you actually observed these occurrences or if you are estimating; Host species count totals; Final nest fate


A group is a collection of nest sites. There is no scientific reason for grouping nest sites, but this is provided as a convenience for NestWatchers to find active nest sites and nesting attempts within our data entry system. You may find it convenient to group nest sites for things like a nest box trail, your yard, or a local park. You can add nest sites to groups using the “Manage your groups” feature.

Archived Nest Site

If you have a nest site that you no longer check, no longer have access to, or is no longer there, you can hide the nest site from showing up within your data entry dashboard. This frees up some clutter but keeps the nest in our database for scientific analysis. Should you ever need to resume entering data for this nest site, you can reactivate the nest using the “Manage Archived Nests” feature.

Cornell Lab of Ornithology

Cornell Lab of Ornithology