- 36 species worldwide
- DR personal total: 20 species (55%), 19 photo'd
Cormorants are a fairly large family of fisheaters residing along
freshwater and saltwater shores around the world, yet all are so
closely related that all are usually placed within a single genus Phalacrocorax.
Despite spending much time in the water, they do not possess the
waterproofing oil of other seabirds and so must spend much time drying
their wings. That's what the Crowned Cormorant at Cape Town, South Africa, is doing (left).
are found almost everywhere that water meets shore. They use
traditional sites for roosting, sunning, and nesting. These tend to be
on islets, jetties, docks, or drowned trees with a 360 degree view to
avoid predators. Cormorants are often easy to see, but they can be quite difficult to approach.
Their hooked bills and bare pouches have evolved to deal with fish; details can be seen on this close-up of the head of Neotropic Cormorant (right), a photo I took out the car window in the Brazilian Pantanal where this species is abundant.
As an aside, the Neotropic Cormorant used to be known as "Olivaceous Cormorant P. olivaceus" but recent research (Browning 1989) showed that the earlier-described brasilianus
was this species, and Neotropic Cormorant defines the species' range
quite well. The 7th ed. A.O.U. checklist (1998) accepts these changes,
although Orta (1992) didn't approve.
Where I live in Monterey, California, our common coastal species is Brandt's Cormorant,
which has taken over the jetty of the harbor as a breeding locale
within the last decade (below). These rocks were once claimed by
sea-lions (and still are in winter) but now, in spring, the cormorants
are king of the jetty.
Although rather a plain bird
most of the year, the adult Brandt's Cormorant in breeding condition
(left) is very impressive in its breeding finery (white plumes on the
head) and exotic displays with the colorful throat pouch (left). Here
on the central coast of California, the displays are underway in
March-April; eggs are laid in April-May; and youngsters are in the nest
June-July (Bailey 1993).
timing of breeding is tied to lattitude and prey populations. Colonies
in southern California are a month earlier; those to the north can be a
month later to initiate (Ainley & Boekelheide 1990).
bright colors of bare skin in courting adults are quickly lost when the
eggs are laid and there is no more pressure to attract mates. By the
time the eggs hatch, adults are quite cull (right) The new youngsters
are very ungainly and almost reptilian. It will take six weeks for them
to grow to full size and fledge.
This species — as are
other cormorants around the world — is very susceptible to highs and
lows in breeding success, depending on sea surface temperatures and the
abundance of their piscine prey. In 'warm water' years, when the prey
base can completely collapses and there is nothing to feed the young,
the entire nesting colony can be abandoned at mid-season (Ainley &
Brandt's are also particularly
susceptible to calamities such as oil spills, as they tend to breed in
large colonies at few sites. Placing all their eggs in just a few such
baskets, if you will, can be tragic if the oil spill is nearby.
on land, cormorants form colonies that are safe from mammalian
predators. These can be offshore islets or jetties, but some build
nests (or use old heron nests) in bare dead trees in water or perched
on inaccessible cliffs. A colony of Pied Cormorants in New Zealand is shown (below); the North American Double-crested Cormorant (left) does the same.
Speaking of Double-crested Cormorant,
it is among the most misnamed species in English, as its "double crest"
of black-and-white wisps is present only during a transient time during
the breeding season (above left), when the pouch and eye color also
Another badly misnamed species, both in English and in its Latin scientific name, is Pelagic Cormorant P. pelagicus
(left) of the northeast Pacific. While it breeds on oceanic shores, it
almost never ventures more than a mile offshore. It is actually the
least "pelagic" of the three species on Monterey Bay — Brandt's and
Double-crested are regularly seen farther offshore.
Cormorant does have a lovely purple and green gloss on its feathers,
especially apparent in breeding season, when it also also a blazing
white flank patch. Like many other cormorants, the bare facial colors
intensify at this season. In the spring, the face of an adult Pelagic
Cormorant is an intensely bright, deep red. It is very dull reddish the
rest of the year.
cormorants use traditional breeding and roosting sites, their droppings
layer up, staining the rocks year after years. In dry areas where rain
does not regularly wash the rocks, such as on the islets of the coast
of Peru, this guano [the Quechua word for excrement] has built up for
2000 years. This guano is rich is nitrates and during the 19th century
there was a major demand for the guano for fertilizer. From 1948–1875
some 20 million tons (!) were exported from the guano islands of Peru
to the U.S. and Europe (Orta 1992). The predominant cormorant here,
named for this phenomena, is Guanay Cormorant
(right). The occur along the Peruvian coast is vast numbers during
normal upwelling times, but populations are decimated and dispersed
during major El Niños.
|The three species shown below include two tropical species — Little Pied Cormorant (left) of Australasia and the "white-breasted" race of Great Cormorant of tropical Africa (right) — flanking a nest of Antarctic Shag (center; photo by Greg Lasley).
|Some older African books consider the white-breasted race lucidus to be a separate species, but more modern texts tend to lump it with the worldwide Great Cormorant P. carbo (e.g., AOU 1998). But it is the southern shags — especially the
"blue-eyed shags" of which the Antarctic is usually considered one of
3–4 species — where there is most debate about species-level taxonomy.
There are separate populations on many subantarctic islands — such as
Heard, Crozet, Kerguelen — that are usually considered subspecies of
Imperial Shag P. atriceps. Orta (1992) splits them all. Other
questions arise about allopatric island populations in and south of New
Zealand. We can expect more research on these topics in the future.
Photos: The sunning Crowned Cormorant Phalacrocorax coronatus was at Cape Town, South Africa, on 1 July 2005 The close-up of Neotropic Cormorant P. brasilianus was taken in the Brazilian Pantanal in August 1999. Scenes and individual Brandt's Coromant P. penicillatus were at Monterey, California, in March (courtship) & July (nestlings) 2006. The Double-crested Cormorant P. auritus was at Monterey in May 2008. The colonial Pied Cormorants P. varius were at Helena Bay, North I., New Zealand, in Dec 1997. The flying Guanay Cormorant P. bouganvillii was just off the Paracas Peninsula, Peru, on 12 June 1987. The Little Pied Cormorant P. melanoleucos was near Sydney, New South Wales, Australia, in Sep 1983. Greg Lasley photographed the nesting Antarctic Shag P. bransfieldensis on the Peteman Is., Antarctica, on 20 Jan 1999. The Great ("White-breasted") Cormorant P. carbo lucidus
was on Lake Nakuru, Kenya, on 17 Nov 1981. All photos © D.
Roberson except the shag, © Greg W. Lasley and used with
permission; all rights reserved.
There is no "family book" per se of which I'm aware (there are numerous
coffee-table "survey" books that include cormorants among other
waterbirds), but a good introduction to the family, with a fine
collection of color photos, is in Orta (1992).
Ainley, D.G., and R.J. Boekelheide, eds. 1990. Seabirds of the Farallon Islands. Stanford Univ. Press, Palo Alto CA
American Ornithologists' Union. 1998. Check-list of North American Birds. 7th ed. A.O.U., Washington, D.C.
Bailey, S.F. 1993. "Brandt's Cormorant," pp. 54-55 & 63 in
Roberson, D., and C. Tenney, eds., Atlas of the Breeding Birds of
Monterey County, California. Monterey Pen. Audubon Soc., Carmel CA.
Browning, M. R. 1989. The correct name for the Olivaceous Cormorant, "Maiague" of Piso (1658). Wilson Bull. 101: 101-106.
Orta, J. 1992. Family Phalacrocoracidae (Cormorants) in del Hoyo, J., Elliott, A., & Sargatal, J., eds. Handbook of the Birds of the World. Vol. 1. Lynx Edicions, Barcelona.