Upon catching the birds, a team of scientists and volunteers attaches metal leg bands, colored flags, and nanotag transmitters. Birds are then processed for a series of metrics, including weight and various physical measurements. After each bird is outfitted and measured, they are immediately released back into the wild to continue their activity.
Banding projects to study migratory shorebirds have been underway since the mid 1990's. In recent years, the birds have been tagged with engraved markers allowing identification of individuals with spotting scopes. The combination of banding and resighting data allows greater understanding of the habitat uses and needs by imperiled species. With this understanding comes the hope of achieving the protective actions required to halt, and even reverse, the population decline exhibited by many shorebird species.
The birds' weight can give us an idea of whether it has enough food to make it to its breeding grounds. Delaware Bay is a critical stopping ground for shorebirds on their northern migrations, as the horseshoe crab spawn results in millions of eggs for hungry birds to forage. Arriving birds blanket the beaches in a feeding frenzy to gain sufficient weight to complete their migration to the Canadian Arctic.
For red knots specifically, 180 grams is considered the minimum weight to reach the breeding grounds in adequate breeding condition. The percentage of trapped birds that weigh at least 180g, or the P180, is an important metric that can indicate the condition of the season's breeding population. If a bird does not reach P180 before leaving for their breeding grounds, there is a risk they will not survive the journey, or will not be in sufficient condition to breed once they reach their destination.