Black Skimmer Life History

Habitat

Habitat Shorelines

Black Skimmers spend their entire lives in coastal areas, usually around sandy beaches and islands, although a few colonies can be found in inland locations with very large lakes, particularly in Florida and California. Nesting birds use open sandy areas, gravel or shell bars with sparse vegetation, or broad mats of wrack (dead vegetation) in saltmarsh. Foraging birds frequent places that concentrate prey: tidal waters of bays, estuaries, lagoons, creeks, rivers, ditches, and saltmarsh pools. Because so many coastal habitats have been developed or otherwise modified, skimmers have become limited in their distribution over most of their range.

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Food

Food Fish

Black Skimmers forage mostly when winds are light and ​waters calm. They take many species of fish, mostly under 5 inches long, and a few crustaceans, such as shrimp or blue crab (when the crabs are molting). Documented prey items include killifish species (such as mummichog), smelt, flounder, menhaden, bay anchovy, spot, bluefish, silversides, herring, pipefish, sea trout, mullet, snapper, Spanish mackerel, and sharksucker. In tidal areas, they often forage in sync with the tides, commonly with bouts just after low tide and just before high tide, but there are many variations.

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Nesting

Nest Placement

Nest Ground

Black Skimmers lay eggs directly on sandy, shelly, or stony ground, usually on islands or remote beaches that have at least a little vegetation. Some nest in the higher parts of saltmarshes. They often nest near or among tern colonies, which (despite numerous squabbles) can provide benefits, as terns aggressively attack gulls and mammals that prey on eggs and chicks.

Nest Description

Mates take turns scraping, using an exaggerated posture (with the neck, head, bill, and tail raised) to kick sand behind them with alternating foot strokes. They then rotate in their scrape to create a saucer-shaped depression, similar to the resting scrapes they use throughout the year. The depression takes only a few minutes to create, and the birds may make several scrapes before eggs are laid. Males do more scraping and make larger scrapes than females. The average scrape is 10 inches in diameter and 1 inch deep.

Nesting Facts
Clutch Size:1-5 eggs
Number of Broods:1 brood
Egg Length:1.5-2.0 in (3.9-5.2 cm)
Egg Width:1.2-1.4 in (3-3.5 cm)
Incubation Period:21-25 days
Egg Description:Pale cream, white, greenish, or pinkish spotted with dark brown to black.
Condition at Hatching:Almost helpless, covered in tan down. Chicks can soon stand and move around, but parents must feed them for 3-4 weeks after hatching
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Behavior

Behavior Aerial Forager

To the birder, mention of “Black Skimmer” brings to mind a bird in elegant repose or effortless flight. Watching them at a nesting colony, from a respectful distance, will uncover additional behaviors. Resting skimmers often put their entire bodies, including head and bill, on the sand, probably to keep cool and to give their neck muscles a break from supporting their large bills. When napping in a flock, skimmers tend to remain standing, and the birds on the outer edges of the flock tuck their bills into the wing on the outer side, keeping an eye out for danger. During the nesting season, skimmers are quite active and are surprisingly agile when walking. Their various displays, like those of terns, can be entertaining to watch. Newly formed pairs sometimes fly in tandem, fluttering up together and flying around the nesting area. They also parade through the area together with necks outstretched and bills held up. Males are protective of their small territories (around the nest) and guard females against interlopers, often using warning displays such as tossing the head upward, standing upright, or facing downward with the tail cocked upward. Sometimes, skimmers open the bill, exposing a reddish gape. Some of these warnings are accompanied by soft, barking calls. Courting males usually present a fish to the mate; copulation is accompanied by a wing-flagging display on the part of the male.

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Conservation

Conservation Declining

Black Skimmers are in decline. The North American Breeding Bird Survey estimates that populations declined 4% per year between 1966 and 2015, indicating a cumulative loss of 87% of their population over that period. Black Skimmers rate a 14 out of 20 on the Continental Concern Score and is included in the Partners in Flight Yellow List for declining populations. The North American Waterbird Conservation Plan estimates the North American population at 65,000-70,000 breeding Black Skimmers and lists it as a Species of High Concern. The main threat to skimmers is development or other loss of their beach-nesting habitat, since they nest on the kinds of beaches that people like to vacation on. In addition to habitat loss, skimmer nests can be destroyed by roaming dogs and by vehicles that are allowed to drive on beaches. Storms and high tides can swamp eggs or nestlings. Projections of sea-level rise suggest further steep declines in Black Skimmer numbers during the current century without management interventions. Because Black Skimmers nest very close to the water’s edge and feed from the water surface, they were among the species of greatest concern during the 2010 Gulf oil spill. By the end of that year, 263 dead Black Skimmers had been collected during the oil spill response.

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Credits

Gochfeld, Michael and Joanna Burger. (1994). Black Skimmer (Rynchops niger), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Kushlan, J. A., M. J. Steinkamp, K. C. Parsons, J. Capp, M. A. Cruz, M. Coulter, I. Davidson, L. Dickson, N. Edelson, R. Elliott, R. M. Erwin, S. Hatch, S. Kress, R. Milko, S. Miller, K. Mills, R. Paul, R. Phillips, J. E. Saliva, W. Sydeman, J. Trapp, J. Wheeler and K. Wohl (2002). Waterbird conservation for the Americas: The North American waterbird conservation plan, version 1. Washington, DC, USA.

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, USA.

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