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| An adult white tern on Midway Atoll |
Not long after arriving at Midway I had an un-nerving
experience. I was walking down the road
when I suddenly realized that I was being followed. Not by a person but by
several small, brilliantly white, birds with long blue bills. Their wings beat
quickly as they flew just a foot or two over me making hoarse “wreck wreck
wreck” sounds. They seemed to want to land on my head or my shoulder and so I
extended my hand to see if one would light, but they didn’t seem interested in
getting quite that intimate. This is typical behavior for manu-o-Kū – the white
tern!
White (sometimes called “fairy”) terns are small seabirds
found across a wide portion of the tropics including the Atlantic, Pacific, and
Indian oceans. They occur throughout the
Northwestern Hawaiian Islands but if you are visiting the main Hawaiian Islands
you will find them only on the south shore of Oahu where a small population persists
around Honolulu. At one time, white terns probably also occurred on the other
main islands (e.g., Kauai) before cats, rats, dogs and other predators wiped
them out. Unlike many seabirds that nest on the ground, white terns like to
nest up high in shrubs or trees. And they don’t actually build a nest, they
simply find a place that they think will hold an egg securely (the female lays just
one) and “nest” there. On Midway typical nesting sites for white terns include
ironwood trees and shrubs like plumeria and tournefortia, especially where a
branch forks creating a small depression. But they also nest on air
conditioners, windowsills, garbage can lids, utility boxes, and other odd
places. After a short fall hiatus, “tern season” begins in December with the
first chicks born around March and peaking during the warm summer months of
June, July and August.
The white tern holds a special place for the Hawaiian people
which is reflected in its native name (manu
means bird and Kū is one of the four
great Hawaiian gods). Moreover, the Hawaiian people have likely had a close relationship
with this bird for hundreds if not thousands of years. Ancient Polynesian voyagers
used white terns to navigate as they are one of the most reliable indicators of
land. Compared to albatrosses and other far-ranging seabirds, white terns stick pretty
close to home (within a hundred or so miles). Like a suburban commuter, terns
leave their islands each morning to spend the day at sea foraging, returning each
evening. If the navigator of a canoe wanted to find land, he’d look for white
terns flying and, depending on the time of day, either head in the direction
they seemed to be coming from (morning) or follow it back towards land
(evening). Terns follow us and vice-versa.
My experience with white terns at sea is mostly limited to
swimming where I often find myself being followed by a small, raucous flock.
What is it that makes the tern want to follow people whether on land or in the
water? I’m not sure anyone really knows. It could be that they are just very curious creatures. This would jibe with one
of their other interesting behaviors which is to sit on a windowsill looking
inside towards the occupants. Many a morning I have eaten breakfast under the
dark black, watchful eyes of one or two white terns.
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| A pair of white terns investigating me from the windowsill of my house |
I have also enjoyed watching white terns forage from my
favorite relaxation spot out on the cargo pier. Terns fly low over the water
looking for small fish near the surface and then swoop down quickly to capture them
in their bills. When foraging to feed their chicks they have to gather several
fish at a time and somehow they are able to do this – catching fish when they are
already holding one or more crosswise in their bills.
Everything about this bird seems surreal. Its pure white
plumage punctuated with blue beak, legs, and feet. It’s habit of fluttering
around you like some spirit animal. Like most other native birds on Midway,
white terns have virtually no
natural predators and as a result do not seem to have much fear of people
and, thus, can be approached at very close distance allowing you to really feel
a part of their world. This extends to their sex life as well and it is common
to see birds engaged in either foreplay or copulation, the former of which
consists of intense, alternating, preening of one another. White terns are
thought to pair for life, which can mean a very long time and courtship
behaviors – which includes high altitude “couples flights” help maintain their pair
bonds. And then there are the chicks. One day there’s an egg on your windowsill
and the next you find a tiny white and brown ball of fluff with oversized,
webbed, feet. The parents share equally
in both incubation and feeding. Parents fly out to sea and return with a
beakful of a whole fish which seem impossibly large for the chick to swallow
but the little fluff ball somehow always manages having what seems like insatiable
hunger. As the chick grows, the size of the fish brought to it increases
commensurately.
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| It takes about 48 days after hatching before a chick is ready to fly. Clockwise from upper left: White tern egg on windowsill; a newly hatched chick; 2 week old chick; 1 month old chick. |
During the summer it’s sometimes necessary to relocate a chicks and raise them in captivity. This happens when some project – for example, tree removal
– eliminates the chick’s “nest site”. As the chick's parent can no longer find it, the chick must be fed by hand. Each day volunteers make three trips to the “white tern nursery”, located just down the road from
the office, where branches have been affixed to large ironwood trees to create safe
places for the chicks. Volunteers then feed the chicks regular meals of Great
Lakes smelt, by hand, three times a day until the chicks are big enough to feed
on their own. This is, without doubt, one of the best jobs there is on Midway
as when the chicks get big enough to fly they actually follow the lucky fish
dispenser back and forth from the office begging for treats.
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| Fledgling white tern chicks swoop down to take smelt from the hand of Fish and Wildlife Service volunteer Aisha Rickli-Rahman |
It seems that nearly everything about the white-tern lends
itself to superlatives; and even the scientific name of the species – Gygis alba – reveals the sublime effect
this bird seems to have on the imaginations of those lucky enough to spend time
around them: the genus, Gygis, is a variation of the ancient
Greek word “guges” which means “mythical bird”.
So maybe at this point you’re wondering where the “noddy”
ties into this story or, maybe, you’re even cynically thinking that in the
title of this post I have crassly sacrificed good natural history for the love
of bad puns. Fear not! Another name for the white tern is “white noddy”, noddies being a
collection of taxonomically-disparate, fork-tailed seabirds in the family Laridae.
White terns are not the only noddies on Midway as we are “blessed” with
both brown noddies and black noddies not to mention several species of terns –
sooty tern, gray-backed tern, little tern, and least tern. Clearly, I don’t
have time to do justice to all of these species here but maybe I can at least
provide a proper introduction.
Black and brown noddies, as the name would suggest are most
similar to white terns in terms of habitat and behavior. Both are common at
Midway and, if they were easier to tell apart, I might be able to tell you more
about how they differ. My understanding is that the black is less common as it
is an obligate-tree nester while the brown noddy can nest in either tree or on
the ground. Brown and black noddies are more likely to form small flocks than
is the white tern and gangs of them can often be seen on the beach this time of
year. These birds seem to share the predilection of white terns for following
swimmers and they also often accompany me on swims.
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| A brown noddy perches on an old ironwood stump on Eastern Island (Midway Atoll) |
Let me also tell you about the sooty tern! These easily-riled birds are not common on
Sand Island but are found in astonishing abundance on the other two islands of
the atoll where people are scarce. Sooty terns are gregarious ground nesters
that form large colonies on Eastern and Spit Islands. During their nesting
season – which lasts from April until October – they blanket areas of the atoll
and must be avoided at all cost. Should you fail to be pay proper attention and
happen to walk too close to one of their colonies you will trigger them to take
off, creating a swarm of thousands of screaming birds. You may be temporarily
deafened and notice that one of them is now swooping down and try to take a
piece of flesh from your face! You may then also suddenly find yourself walking
among their well-camoflaged eggs and
praying that you don’t accidentally step on one. Gray-backed (or
spectacled) terns are rarer than the Sooty tern, but no less easily
agitated and tend to nest around the edges of the sooty tern colonies. They
must also be treated with extreme caution.
As for the final two terns on our list, the little and the least (seriously, who comes up with these names), they are both pretty rare and exciting to see. Being the mediocre birder that I am, I have
little to report but a few random sightings that I probably would not have even
noticed were it not for the astute observations of others. But they are here and the breaking news is that the least terns are currently nesting!
If you are a regular reader of this blog you may have
thought, until now, that Midway was all albatrosses and petrels. I hope that this short detour into the lives
of other important and interesting seabirds that inhabit the atoll gives you a more complete appreciation of the bird life here. And there is more! You can look forward to a couple more bird-related blog posts in the future.
