The black skimmer (Rynchops niger) is a very unique bird species that is found along coastal areas in North and South America. With their distinctively large red and black bills, black skimmers stand out from other shorebirds. But beyond their unusual appearance, black skimmers have some intriguing natural history that relates to how rare they are.
Some quick answers about the rarity of black skimmers:
– Black skimmers are considered a species of “Least Concern” on the IUCN Red List of Threatened Species. So they are not an endangered or rare species overall.
– However, black skimmer populations have declined in many regions, primarily due to habitat loss and human disturbance. They are considered endangered, threatened, or a species of special concern in several U.S. states.
– Major threats to black skimmers include coastal development, human recreation, erosion, disturbance by pets, and climate change impacts like sea level rise. Their limited nesting habitat preferences make them vulnerable.
– In the United States, black skimmers are more common along the Atlantic coast than the Gulf coast or Pacific coast. So regionally, they are rarer on the Gulf and Pacific.
– Total global population is estimated to be 35,000 – 106,000 adults by BirdLife International. The large range reflects some uncertainty due to the difficulty surveying skimmers across their wide geographic distribution.
Black Skimmer Biology and Identification
Black skimmers are tern-like waterbirds in the family Rynchopidae. Two characteristics make them unique among North American bird species:
– Their large red and black bill is horizontally compressed side-to-side with a longer red lower mandible. The lower mandible tapers to a sharp point.
– They have a distinctive skimming feeding behavior, flying along just above the water surface with their lower bill partially submerged. The bill snaps shut when they contact a fish.
Adult black skimmers have black crowns, napes, wings, backs and tails contrasting sharply with their white undersides. Their legs are bright red-orange. They have a wingspan of around 50 inches.
Juvenile skimmers have a blotchy black-and-white pattern instead of the crisp delineation between dark and light plumage. Their bills start out a drab gray before obtaining the adult red and black coloration.
Breeding
Black skimmers breed in scattered coastal colonies ranging from around 25 to over 3000 nesting pairs. They nest on bare or sparsely vegetated sand, shells, or gravel substrates. Nest sites are often on sandbars, barrier islands, beaches, and dredge spoil islands.
Both sexes assist in nest construction by scraping out a shallow depression or lining a natural hollow with shells and debris. Eggs are buff to cream colored with dark brown spotting. The typical clutch size is 3-5 eggs.
Incubation ranges from 21-26 days and is performed by both sexes. The semi-precocial downy chicks hatch with eyes open and leave the nest within a day. Parents shelter chicks under their wings during the day. Chicks fledge in about 28 days.
Diet
Black skimmers are piscivores, meaning fish make up the majority of their diet. They forage predominantly at dawn and dusk. Their unique bills allow them to fly along skimming the water’s surface, snapping shut on any fish that touch the lower mandible. Common prey includes species such as mullet, menhaden, silversides, killifishes, and minnows. Skimmers may also occasionally eat crustaceans and insects.
Migration
Black skimmers that breed in the United States and Mexico migrate between their summer breeding range and wintering range in Central and South America. Migration peaks in late August and early September. Wintering areas extend from Mexico to southern Brazil and northern Argentina. Northern populations migrate the farthest.
Population Status and Conservation
The global population of black skimmers was estimated at 35,000 to 106,000 mature individuals in 2016 by BirdLife International. However, their overall population trend is decreasing. Here is a summary of their status:
Global Population and Trends
- Global population estimate: 35,000 – 106,000 mature individuals
- Global population trend: Decreasing
- IUCN Red List category: Least concern
United States Population
- Estimate of 10,000 – 26,000 breeding pairs in the U.S. as of 2003 (most recent estimate available)
- Largest populations found along the Atlantic coast
- Population declined 3.7% annually 1966-2003 per Breeding Bird Survey
State-Level Status
Black skimmers are listed as endangered, threatened, or of special concern in the following states due to steep population declines:
- Massachusetts – Endangered
- New Hampshire – Endangered
- New Jersey – Threatened
- North Carolina – Threatened
- Florida – Threatened
- Wisconsin – Special Concern
Threats and Conservation Challenges
Several key factors contribute to declining black skimmer numbers in parts of their range:
Coastal Habitat Loss
Coastal development for homes, businesses, and recreation destroys and degrades skimmer nesting habitat. Erosion can also eliminate suitable nesting beaches. For example, between the 1940s and 1980s, over 60% of saltmarsh habitat was lost in Massachusetts, greatly reducing skimmer nesting habitat.
Disturbance
Black skimmers are highly vulnerable to human disturbance and predators at their nesting colonies. Beach recreation, off-road vehicles, loose dogs, and increases in predators due to human presence have caused nest abandonment and colony relocation. For example, repeated colony abandonment was documented due to fireworks on a Massachusetts colony.
Sea Level Rise
Rising sea levels from climate change are projected to inundate and alter many coastal habitats used by nesting black skimmers. Sea level rise was linked to regional population declines in Texas.
Other Threats
Other issues facing black skimmers include:
- Oil spills – contamination and habitat degradation
- Fishing bycatch – becoming caught in fishing gear
- Pesticides – may reduce prey fish populations
- Extreme storms – can wipe out colonies
Because black skimmers nest colonially and rely on limited coastal habitats, they are especially vulnerable compared to other more adaptable bird species.
Conservation Actions
A number of conservation actions help protect and manage black skimmer populations including:
– Protecting and managing known nesting sites. For example, fencing and signage to reduce human disturbance.
– Habitat restoration and creation of artificial nesting sites, such as dredge spoil islands.
– Restricting vehicle access and pets in sensitive beach habitats.
– Public education and outreach to reduce disturbance and increase awareness.
– Monitoring and surveying populations to detect trends.
– Predator control at nesting sites when necessary.
– Legislation to protect coastal habitat and prevent further losses.
– Partnering with groups like The Nature Conservancy who actively manage skimmer nesting habitat in places like North Carolina’s Cape Lookout National Seashore.
More conservation focus is needed, especially anticipating and preparing for future sea level rise impacts on threatened coastal nesting habitats. But targeted management and habitat protection can help maintain black skimmer populations.
Conclusion
While black skimmers have an extensive range throughout the Americas, they face population declines in many regions because of their specialized coastal habitat needs and vulnerability to human disturbance. They are considered endangered, threatened or of conservation concern in several U.S. states. But global populations remain reasonably stable, leading to an IUCN designation of Least Concern. Targeted research, monitoring, and on-the-ground management of nesting habitat and breeding colonies are critical conservation approaches for maintaining black skimmer populations into the future. This unique species provides an opportunity to promote seabird conservation and ensure suitable coastal habitat protection overall.