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Skip Navigation LinksDNREC : Division of Fish & Wildlife : Shorebirds

 
Research and Monitoring

 

Each each May, the Delaware Shorebird Project works intensively to carry out its research objectives during the shorebirds’ stopover in the Bay. The brief field season is characterized by long days out on the water, in the sand, and in the lab using the following kinds of research methods.

Volunteers capturing shorebirdsBird Capture

  • Cannon Netting
  • Bird Capture
  • Banding
  • Body Measurements

Data collected supports the following research goals:

Shorebird Health and Condition
The ability of birds to gain weight throughout the season is critical to our understanding of the conditions shorebirds encounter on the Delaware Bay. Novel approaches to analyzing weight gained throughout the season will be used to assess the birds’ ability to put on weight (energy reserves) while they are here. 

Winter Populations
Molecular analysis of Red Knot feathers that were molted on the wintering grounds and collected in Delaware Bay has revealed four distinct wintering areas: Bahia Lomas, Chile; Rio Grande, Argentina; Southeast U.S. (FL and GA); and Northern Brazil/Caribbean.  There may be important fitness and survivorship consequences for Red Knots depending on where they spend the winter. This work will continue this year and the results will ultimately be compared to survivorship estimates for wintering groups, arrival/departure dates, movement patterns, and weight gain.

Volunteer Shorebird Watcher Resighting

In brief, this includes scanning with scopes for birds marked as individuals with encoded flags. Data collected supports the following research goals:

Stopover Duration
Monitoring the Delaware Bay passage requires knowledge of how long birds stay in the Bay as well as arrival and departure patterns.  It is not sufficient to assume that all birds get to Delaware Bay on May 1 and depart on May 28.  There are observable differences in arrivals of different groups of birds. Knowing when these events happen will potentially allow us to better assess how different populations of shorebirds are using the Bay. Stopover duration is assessed through resighting of flagged birds and radio telemetry data.

Bay-wide Movement Patterns
Determining where birds go in the Delaware Bay during their stopover is a critical part of directing conservation and protection efforts appropriately. Resighting individually-marked birds at various locations throughout the Bay is one method used to evaluate Bay-wide movement patterns.  Advances in technology have allowed us to use an automated radio tracking system to extend the scope of “resighting” birds both spatially and temporally. This system, initially developed to track horseshoe crabs, has been used to track Red Knot movement patterns by attaching radio transmitters to a small group of individuals. The system has allowed us to track the movement of the birds almost continuously during their stopover. Sites important for feeding and roosting are being determined from this work. 

Tagged red knotSurvivorship
Shorebirds, particularly Red Knots, are long-lived species with long distance migratory patterns. Given these characteristics, a variety of factors may impact their populations either positively or negatively. These characteristics also limit our ability to accurately determine and monitor their overall population size. We can, however, assess year-to-year survivorship to help us to monitor their populations. Survivorship is assessed through resighting individually marked birds in subsequent years.

Bay-wide Egg Surveys

  • Sediment Sampling of Prey Availability

Data collected supports the following research goals:

Distribution and Abundance of Horseshoe Crab Eggs
The abundance and distribution of horseshoe crab eggs available to shorebirds will be quantified through a horseshoe crab egg survey.  This survey will provide an index of horseshoe crab egg abundance, which can be used to help determine whether there are sufficient eggs available to shorebirds to support their energetic requirement for migration and artic breeding.  In addition, it will help us to monitor shifts in distribution and trends in egg density in relation to shorebird use among years.

Disturbance Studies
Shorebirds using Delaware Bay as stopover site encounter a number of challenges including Bay-wide variations in food availability, weather, and predators. One challenge birds have are disturbances to feeding and roosting sites. These include predators, humans (beachcombers and researchers), boats, planes and dogs. 

Other Research Methods employed by the Delaware Shorebird Project include:

  • Mist Netting
  • Radio Telemetry
  • Horseshoe crab harvest model

 

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