Endangered nesting birds settle on new islands

Several species of threatened or endangered colonial nesting birds make the Maryland coastal bays their home.

In Maryland, least terns are listed as threatened while black skimmers and royal terns are listed as endangered. Sandy beaches are necessary for colonial nesting birds, as that is the habitat on which they build nests.

Unfortunately, this habitat is becoming harder to come by in the Maryland coastal bays. Development, erosion and sea-level rise are all factors that have taken away valuable nesting area for these bird species. The islands that dot our coastal bays are the last remaining refuges for these birds because they are ideal habitats mostly devoid of possible predators such as foxes and raccoons and they provide the sandy beaches that are essential to these birds.

Black skimmers are one of the three species of skimmers found worldwide and are the only species of skimmer found in North America. Skimmers have a unique bill with a lower mandible that is longer than the upper one; it’s bright red in color at the base but black at the tip.

Black skimmers are named for their feeding habits, which utilize that unique bill. They skim along the surface of the water, dipping the lower mandible in the water and pulling prey from the water. Nest sizes are normally between two to five chicks that require parental care for about a month after hatching.

Royal terns are among the larger of the tern species, one of six species of “crested” terns. During breeding season, royal terns have a distinctive black crown around their heads, hence the “crested” status.

Each breeding season, mating pairs will lay a single egg. After hatching, chicks congregate to form a single group within the colony. Royal tern parents will only feed their own chicks and recognize their offspring’s calls among the group.

Black skimmers and royal terns nest in large groups, often with other species of birds such as the laughing gull or the least terns, hence their inclusion in the colonial nesting bird group.

Colonial nesting bird populations have declined in Maryland for a variety of reasons. In the 19th century, skimmer eggs were collected commercially and a large number of these birds were hunted as well.

Royal tern eggs were also known to be commercially collected. but on a smaller scale than the skimmers.

Today, the biggest reason for colonial nesting bird decline is habitat loss. After the hurricane of 1933, 29 of the original islands used as habitat by these birds were created in the coastal bays from a combination of natural accumulation and dredge deposits.

Recent research indicates in the 24 years between 1980 and 2004, 300 acres of island were eroded away. Now only three of those original islands remain; however, a solution is available to create more habitable area for these birds.

The Army Corps of Engineering received money to dredge the federal navigation channel in the coastal bays. Herein lies part of the solution. The dredged material from the project needed to be put somewhere, so the solution was to create islands in the coastal bays using the dredged sand.

Creation of four new islands began last November and will be completed at the end of this summer. The dredging was necessary to maintain the channels and was funded by the Federal Disaster Relief Appropriation Act of 2013 in response to Hurricane Sandy.

The islands created are considered natural resources of the state of Maryland and are under management of the Department of Natural Resources as wildlife management areas.

The islands will be beneficial to many species of wildlife in the bays, including the colonial nesting birds. Terrapins may use the islands for nesting areas, horseshoe crabs for mating and spawning, and shorebirds during fall for resting places.

In the event that black skimmers or royal terns do nest on the island, the island would be closed to the public during nesting season. Human disturbances can greatly impact the reproductive success of the birds.

Since these are colonial nesting birds, they tend to nest together on one single island. This means a disturbance would scatter the birds, leaving eggs and chicks exposed. With repeated or continued disturbances, high chick loss can occur, which leads to less population recruitment for the species.

This year, only six black skimmers built nests in Maryland. All six skimmers were nesting on one tiny island that was in a precarious position in the Isle of Wight Bay. The chicks were at risk of being washed away by boat wakes during high tides.

The new islands will provide a safer nesting area with less danger of being washed away.

Unfortunately, royal terns are not faring much better in the bays. This year, only 44 royal tern chicks were recorded; in past years, nests of more than 200 chicks have been observed. This population reduction in population is a result of lack of sandy areas on which to nest and raise their young.

It is vital for the preservation of these species in Maryland to maintain these islands as wildlife habitat and to respect their needs.

Katherine Phillips is the science intern for the Maryland Coastal Bays Program.