The Storm-Petrels are a widespread family of small seabirds found throughout
the oceans of the world. About half the species are highly migratory, spending
the summer month in rich cold waters far north or far south, and then moving
toward the subtropics in the winter months. One of these migratory birds
is the lovely Fork-tailed Storm-Petrel (left) which breeds on tiny
islets from Japan & Alaska south to northern California, and then disperses
widely over deep oceanic waters in the non-breeding season. Where I live
on Monterey Bay, California, this is a species generally found only far
offshore. Occasionally, strong NW gales in spring or fall will force hundreds
into Monterey Bay itself, and for a few days thereafter birds can sometimes
be seen from shore; I took this photo from Monterey's commercial wharf
during one such incursion. The Fork-tails blown inshore try to get back
offshore as soon as possible; otherwise, local Western Gulls find they
can prey on them quite easily, and storm-petrels inshore don't dare remain
there long. |
 Storm-petrels,
like other members of the order Procellariformes, have specially modified
"tubes" atop their bills. This special organ -- which you can see in this
in-hand photo of a Leach's Storm-Petrel (right) -- allows them to
drink salt water and then dispose of the salt. One can sometimes see drops
of concentrated sale being "sneezed" out of these tubes. The Leach's Storm-Petrel
must be one of the world's commonest species. Nesting in the North Pacific
on islets from Alaska to Baja, they disperse across the eastern tropical
Pacific in the millions during the northern winter. This in-hand individual
was one such bird, running into the research ship I was on at night, probably
distracted by our lights. The spot was just north of the Equator, and about
500 west of Ecuador, so it was really out in the middle of nowhere. [The
Wilson's Storm-Petrel Oceanites oceanicus, breeding on sub-Antarctic
islands, disperses in the millions into the Atlantic, and some have opined
that it is the world's most abundant bird.] |
The other half of the storm-petrel species are primarily tropical, staying
within warm waters but wandering widely as food can be patchy and hard
to find. One species of deep offshore warm waters is the Band-rumped
Storm-Petrel (left; this photo from the Pacific; see Haney 1984 on
western Atlantic distribution). Its basic pattern -- black bird with
a white rump band -- is a feature shared with 8 other species. The bands
vary is size and extent, but identification of these birds can be difficult
[see Crossin (1974), Boswell (1979), Brown (1980), Marsh (1980), Naveen
(1981-1982), and Harrison (1983a) for starting points]. Flight styles and
behaviors are important in identification, and I spent substantial time
during my four months at sea in the eastern tropical Pacific sorting out
some of the distinctions (I have not yet published these notes). Incidentally,
this particular Band-rumped Storm-Petrel shown here was photographed about
50 miles NNW of the Mexican island Isla Clarîon, and thus constituted
the first documented record from Mexico (see Howell & Webb 1995).
Storm-Petrels have incredible powers of smell and therefore can locate
potential items to scavenge from miles away. The Band-rumped Storm-Petrel
just discussed followed in our ship's wake for an hour, quite possibly
attracted to odors emanated from the kitchen for the large research ship,
or oily wastes dumped overboard.
|
Yet another experience on my four months at sea in fall 1989 was observing
one of the world's rarest and least known storm-petrels, the Ringed
(or Hornby's) Storm-Petrel (left two shots). It forages solitarily
over deep water far offshore western South America (Ecuador to Chile) but
its breeding grounds -- possibly somewhere on the mainland in remote dry
deserts -- have yet to be found.
