Endangered nesting birds settle on new
islands
KATHERINE PHILLIPS
4:49 p.m. EDT August 24, 2015
COMMENTARY: It is vital to maintain these islands as wildlife habitat
and to respect the birds’ needs.
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.