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Summary Wayfinding, or Non-Instrument Navigation
by Dennis Kawaharada
Photo: Swells Help a
Navigator Hold a Course in the Daytime
 Introduction
Before the invention
of the compass, sextant and clocks, or more recently, the
satellite-dependant Global Positioning System (GPS), Polynesians
navigated open ocean voyages without instruments, through careful
observation of natural signs. (See
Hawaiian Navigation.)
Navigator Nainoa
Thompson of the Polynesian Voyaging Society, who was taught by Mau
Piailug, a master navigator from Satawal in Micronesia, explains how
a star compass is used to tell direction without instruments: The
star compass is the basic mental construct for navigation. We have
Hawaiian names for the houses of the stars-the places where they
come out of the ocean and go back into he ocean. If you can identify
the stars, and if you have memorized where they come up and go down,
you can find your direction. The star compass is also used to read
the flight path of birds and the direction of waves. It does
everything. It is a mental construct to help you memorize what you
need to know to navigate.
"How do we tell
direction? We use the best clues that we have. We use the sun when
it is low on the horizon. Mau has names for how wide and for the
different colors of the sun path on the water. When the sun is low,
the path is tight; when the sun is high it gets wider and wider.
When the sun gets too high you cannot tell where it has risen. You
have to use other clues.
"Sunrise is the most
important part of the day. At sunrise you start to look at the shape
of the ocean-the character of the sea. You memorize where the wind
is coming from. The wind generates the swells. You determine the
direction of the swells, and when the sun gets too high, you steer
by them. And then at sunset we repeat the observations. The sun goes
down-you look at the shape of the waves. Did the wind change? Did
the swell pattern change? At night we use the stars. We use about
220 stars by name-having memorized where they come up, where they go
down.
"When I came back from
my first voyage as a student navigator from Tahiti to Hawaii the
night before he went home, Mau took me into his bedroom and said "I
am very proud of my student. You have done well for yourself and
your people." He was very happy that he was going home. He said,
"Everything you need to see is in the ocean but it will take you
twenty more years to see it." That was after I had just sailed 7000
miles.
"When it gets cloudy
and you can't use the sun or the stars all you can do is rely on the
ocean waves. That's why he said to me, "If you can read the ocean,
you will never be lost." One of the problems is that when the sky
gets black at night under heavy clouds you cannot see the swells.
You cannot even see the bow of the canoe. And that is where people
like Mau are so skilled. He can be inside the hull of the canoe and
just feel the different swell patterns moving under the canoe and he
can tell the canoe's direction lying down inside the hull of the
canoe. I can't do that. I think that's what he learned when he was a
child with his grandfather.
"The Southern Cross is
really important to us. It looks like a kite. These two stars in the
Southem Cross always point south (Gacrux on top and Acrux on the
bottom). If you are traveling in a canoe and going south, these
southern stars are going to appear to be traveling the higher and
higher in the sky each night. If you went down to the South Pole,
these stars are going to be way overhead. If you are going north to
Hawai'i, the Southern Cross travels across the sky in a lower and
lower arc each night. When you are at the latitude of Hawai'i, the
distance from the top star (Gacrux) to the bottom star (Acrux) is
the same distance from that bottom star to the horizon. That only
occurs in the latitude of Hawai'i.lf you are in Nuku Hiva at 9° S,
the distance between the bottom star in the Southern Cross and the
horizon is about nine times the distance between the two stars."
The following
techniques are used by Hawaiian and Polynesian navigators taught by
Mau and Nainoa. The art, as it is practiced today in Hawai'i, uses a
Hawaiian star compass developed by Nainoa, incorporating principles
from Mau's Micronesian star compass and traditional Hawaiian names
for directions and winds.
The Sun
The sun is the main
guide for the navigator without instruments. Twice a day, at sunrise
and sunset, it gives a directional point to the traveller, as it
rises in the east and sets in the west. The exact direction changes
during the year. As the earth, tilted at at 23.5° angle, orbits the
sun, the sun appears to move in the sky against the background of
the stars along a curving path called the ecliptic and through a
series of 12 constellations called the zodiac. (See "The Ecliptic".)
At the spring and fall equinoxes (Mar. 21 and Sept.23) the sun
appears to be on the celestial equator and rises due east and sets
due west. During the summer, the sun is north of the celestial
equator, rising and setting north of east and west; at summer
solstice (June 21), the sun rises 23.5° north of east ('Aina
Ko'olau, or ENE) and sets 23.5° north of west ('Aina Ho'olua, or
WNW). During the winter, the sun is south of the celestial equator,
rising and setting south of east and west; at winter solstice (Dec.
22), the sun rises at 23.5° S of east ('Aina Malanai, or ESE), and
sets 23.5° S of west in 'Aina Kona (WSW).
Click here for a Diagram
of the Rising and Setting Points of the Sun.
To hold a course, the
navigator aligns the rising or setting sun to marks on the railings
of the canoe. There are 8 marks on each side of the canoe, each
paired with a single point at the stern of the canoe, giving
bearings in two directions, 32 bearings in all to match the 32
directional houses of the Hawaiian star compass.
Click here for a Diagram of the 32 Bearings
Marked onto the Canoe Rails.
The Stars
Like the sun, most
stars rise in particular directions on the eastern horizon, travel
across the sky, and set in particular directions on the western
horizon. The directional house in which a star rises on the Hawaiian
Star Compass has the same name as the house in which it sets (e,g.,
a star rising in 'Aina of the Ko'olau quadrant (ENE), sets in 'Aina
of the Ho'olua quadrant (WNW). The directional point at which a star
sets is at the same angular distance (delincation) and in the same
direction (i.e., north or south) from west as the house in which it
rose is from east. For example, at the equator, Hokulei (Capella)
rises at 46° N of east in Manu Ko'olau (NE) and sets at 46° N of
west in Manu Ho'olua (NW).
Click Here for the Rising Points of the 21
Brightest Stars.
The navigator holds
his course by orienting his canoe to these rising and setting
points. For example, when the navigator with a favorable wind wants
to head Manu Malanai (SE), and a star is rising at the point Manu
Malanai (SE), he points the bow toward the star. If there is no star
rising or setting in the direction he is heading, the navigator can
orient the canoe using a star rising or setting anywhere else on the
horizon, as long as he knows its direction. He keeps the star at a
bearing that will head the canoe in the desired direction.
Click here for a Diagram of Steering by the
Stars.
As wind drift may be
carrying the canoe to the right or left of its apparent heading, the
navigator corrects his steering for this sideway drift, called
leeway ; as the night passes and stars rise and set, moving about 1
degree across the celestial sphere every four minutes, the navigtor
uses as many stars as possible as clues to hold his direction.
If the star is above
the horizon, the navigator imagines a line from it down to its
rising or setting point. The angles at which the stars rise and set
will change with latitude. Only at the equator do stars appear to
rise perpendicular to the horizon. In Hawai'i, at 20° N, stars rise
and set at a 20° angle, leaning south from straight up; in Tahiti,
at 17° south, stars rise and set at a 17° angle, leaning north from
straight up. In other words, the angle at which stars rise and set
from a line perpendicular to the horizon is equal to the latitude of
the observer. The pathways of the stars lean south in the northern
hemisphere and north in the southern hemisphere.
As the navigator moves
north or south of the equator, the rising and setting points will
begin to shift north for stars north of east and west and south for
stars south of east and west The shift will be smaller for stars
near the celestial equator, and greater for stars toward the north
and south celestial poles. (This shifting is due to the changing
angle of the curved surface of the earth over which the observer
sees the sky.)
As the observer moves
toward the poles, the angles of rising and setting of the stars will
tilt closer and closer to the horizon until at the poles, the stars
will not rise or set, but circle around the observer like figures on
a merry-go-round, with the observer standing in the middle. At the
north pole, only the northern half of the celestial sphere is
visible; at the south pole, only the southern half of the celestial
sphere is visible.
A star which angles as
it arcs through the sky is useful for determining direction when it
is within 30-35 ° of the horizon; beyond this it becomes difficult
to tell exactlywhere it rose or will set. At the equator, where
stars rise perpendicular to the horizon, a star may be traced back
to the horizon from a greater altitude.
During a voyage, stars
may be available for navigation only about 20 percent of the time;
daylight and cloud-cover at night hide them from the navigator
during the other 80 percent of the time.
North and South
Pointers
Pairs of stars that
cross the meridian at the same time are oriented north and south.
(The meridian is an imaginary line from due north to due south
passing through the zenith, the point in the sky directly overhead;
the meridian is perpendicular to the horizon; stars move from east
to west through the sky and cross the meridian at the midpoint of
their journeys from horizon to horizon.) Meridian pairs, or
pointers, in the northern sky point north; pairs in the southern sky
stars point south. For example, the top and bottom stars in the
Southern Cross, a meridian pair, point south when the Cross is
upright.
Meridian Pointers to
the North Celestial Pole
-
Alpheratz (00h 8.4m)
+ Polo'ula / Caph (00h 9.2m)
-
Alpha Trianguli (01h
53.1 m) + Segin (01h 54.4m)
-
Theta Aurigae (05h
59.7m) + Menkalinan (05h 59.5m)
-
Puana / Procyon (07h
39.3m) + Nanamua / Castor (07h 34.6 m) & Nanahope / Pollux (07h
45.3 m)
-
Hikulua / Merak (11h
1.8 m) + Hikukahi / Dubhe (11h 3.7m)
-
Cor Caroli (12h 56m)
+ Hikulima / Alioth (12h 54m)
-
Ed Asich (15h 24.9m)
+ Pherkad (15h 20.7m)
-
Gienah (20h 46.2m) +
Pira'etea / Deneb (20h 41.4m)
-
Markab (23h 2.8m) +
Scheat (23h 3.8m)
Meridian Pointers to
the South Celestial Pole
-
Mirzim (06h 27.7m) +
Ke Ali'i o Kona i ka Lewa / Canopus (06h 23.9m)
-
Suhail (09h 08m) +
Star in the False Cross (09h 11m)
-
Cross Dividers: Mu
Velorum (10h 46.8m) + Unnamed star cluster (10h 46.3m)
-
Hanaiakamalama /
Southern Cross: Kaulia / Gacrux (12h 31.2m) + Ka Mole Honua /
Acrux (12h 26.6m)
-
Menkent (14h 6.7m) +
Mailemua / Beta Centauri (14h 3.8m)
-
Alpha Lupi (14h
41.9m) + Mailehope / Alpha Centauri (14h 39.6m)
-
Top stars in Kamakau
/ Scorpio: Dschubba (16h 0.3m) + Pi Scorpii (15h 58.8m)
-
Middle stars in
Kamakau / Scorpio: Epsilon Scorpii (16h 50.2m) + Mu2 Scorpii (16h
52.3m) + Zeta Scorpii (16h 54.6m)
-
Bottom stars in
Kamakau: Kamaka / Shaula (17h 33.6m) + Sargas (17h 37.3m)
The Moon
Like the sun, the moon
travels along the path called the ecliptic; however, it completes it
cycle in 29.5 days-the time it takes for the moon to orbit the
earth. (See "The Moon Along the Ecliptic.") The moon rises about 48
minutes later each night at a different postion on the eastern
horizon from where it rose the night before. Its rising point moves
back and forth between 'Aina Ko'olau (ENE) and 'Aina Malanai (ESE)
during its 29.5 day orbit around the earth; its setting point
between 'Aina Ho'olua (WNW) and 'Aina Kona (WSW). As it changes its
position in relationship to the sun and earth, it goes through 29-30
phases.
The Hawaiian Lunar
Month
In the traditional
Hawaiian calendar, the lunar month was determined by the 29.5-day
cycles of mahina, the moon, and the passage of days were marked by
the phases of the moon. The approximately 30 days of the moon cycle
were divided into three 10-day periods (anahulu). The first 10-day
period was called "ho'onui," "growing bigger."
1. Hilo (faint
thread; cf. puahilo, "faint, wispy").
2. Hoaka (crescent;
arch over the door; Handy and Handy say the name means "faint
light" or "casting a shadow.")
3-4-5-6. Kukahi,
Kulua, Kukolu, Kupau (Literally, First, Second, Third, and Last
Ku)
7-8-9-10. 'Olekukahi,
'Olekulua, 'Olekukolu, 'Olekupau (Literally, First, Second, Third,
and Last 'Oleku. 'Olekulua was the first quarter of the moon; the
names for days 7-10 match the names of days 21-24 of the last
quarter moon; days 7-10 mark the transition from less than
half-lit moon to the more than half-lit moon.)
The second 10-day
period was called "poepoe," "round" or "full," when the moon appears
full and round. The nights of the bright moon-possibly Akua, Hoku,
and Mahe-a-lani- were referred to as "na po mahina konane"; konane
means "bright moonlight."
11. Huna ("to hide";
when the moon hides its "horns" and appears more rounded)
12. Mohalu ("to
unfold like a flower," "to blossom")
13. Hua (fruit, egg)
14. Akua (god; the
first night of fullness)
15. Hoku (the second
night of fullness; if the moon is still out at sunrise, it is
called Hoku ili, "Stranded moon"; if it has set just before
sunrise, it is called Hoku palemo, "sunken moon.")
16. Mahe-a-lani (the
third night of fullness; "mahea" means "hazy, as moonlight")
17. Kulua (E.S.
Craighill Handy, with Mary Kawena Pukui, gives this day name as
"Kulu," which could mean "to drop" or "to pass, as time does")
18-19-20.
La'aukukahi; La'aukulua; La'aukupau (Literally, First, Second, and
Last La'auku; during this sequence, the sharp "horns" of the moon
begin to appear again.)
The third 10-day period
was called "'emi," "decreasing" or "waning." The moon begins to lose
its light. The last quarter moon rises around midnight and sets
around noon. Muku, the new moon, is unseen between the earth and the
sun.
21-22-23. 'Olekukahi;
'Olekulua; 'Olekupau (Literally, First, Second, and Last 'Oleku;
'Olekulua was the last quarter; the names of days 21-23 match the
names of 7-10 days of the first quarter moon, and mark the
transition from more than half-lit moon to less than half-lit
moon. );
24-25-26.
Kaloakukahi; Kaloakulua; Kaloapau (Literally, First, Second, and
Last Kaloaku;
27. Kane
28. Lono
29. Mauli ("ghost,"
"spirit"; Malo: "fainting"; Kepelino: "last breath")
30. Muku ("Cut-off."
The new moon; the end of the moon cycle. The moon is in front of
the sun; its backside is lit; its frontside, facing the earth, is
dark.)
Determining the rising
and setting points of the moon each night in relationship to another
celestial body allows the moon to be used for navigation, day or
night.
The line separating
light and dark on the moon's surface is aligned approximately north
and south since the moon is positioned east or west of the sun as
they travel across the sky.
Hoku hele / "Traveling
Stars" (Planets)
Planets ("Wanderers")
appear to move among the fixed stars over time; hence, their
Hawaiian names hoku hele, "Traveling Stars", or hoku 'ae'a,
"Wandering Stars." Their rising and setting points can be determined
from nearby stars; they can be used for navigation once their
positions have been determined. The Hawaiian names for the visible
planets are:
Mercury: Ukaliali'i
("Following the chief," i.e. the Sun)
Venus: Hokuloa ("Long
Star"), Hokuao ("Morning Star"), Hokuahiahi ("Evening Star"),
Hokuali'i ("Chiefly Star"), Hokuali'iwahine ("Chiefly [female]
Star")
Mars: Hoku'ula ("Red
Star"), Holoholopina'au, 'Aukelenuiaiku ("Great travelling
swimmer, son of Iku")
Saturn: Makulu ("A
drop of mist")
Jupiter: Aohoku
("Starlight"), 'Iao ("Dawn"), Ikaika ("Strong," "Powerful")
Ocean Swells
During midday and on
cloudy nights when celestial bodies are not available at the horzion
as directional clues, the navigator uses the wind and swells to hold
a course. However, the direction of wind and swells cannot be
determined independently; their direction can only be determined by
reference to celestial bodies such as the rising or setting sun.
Swells are waves that
have travelled beyond the wind systems or storms that have generated
them, or waves that persist after the generating storm has died
away. Swells are more regular and stable in their direction than
waves. ("Waves," as opposed to "swells," are generated by local,
contemporary winds.) Sometimes swells can be felt better than they
can be seen, having flattened out after travelling long distances.
In the Pacific, the northeast trade winds generate a northeast
swell; the southeast tradewinds create a southeast swell, and so on.
Storms in the South Pacific during the Hawaiian summer generate a
south swell; storms in the north Pacific during the Hawaiian winter
generate a north swell.
Swells move in a
straight line from one house on the star compass to a house of the
same name on the opposite side of the horizon,180 ° away. Thus, a
swell from the direction of Manu Ko'olau (NE) will pass under the
canoe and head in the direction of Manu Kona (SE); a swell from
'Aina Malanai (ESE) will pass under the canoe and head in the
direction of 'Aina Ho'olua (WNW).
The navigator can
orient the canoe to these swells. For example, if the canoe is
heading SE Manu with a swell coming from the SE Manu, the person
steering keeps the canoe headed directly into the swell, which lifts
the bow, passes beneath, then lifts the stern. If the canoe is
traveling SW, a SE swell would roll the canoe from side to side,
lifting first the port hull, then the starboard hull as it passes
beneath.
After the navigator
orients the canoe to a swell pattern, he gets used to the pitching,
rolling, or corkscrewing of the canoe; when the motion changes the
navigator knows that the canoe is no longer going in the same
direction (assuming the direction of the swell remains constant).
The motion gets complex when more than one swell is running; an
experienced traditional navigator like Mau can feel as many as four
or five swells.
Swells may change
direction after a time because the storm generating them may be
moving. In places such as the doldrums, the swell pattern can be
confused by waves generated by variable local winds from isolated
and passing squalls. When the seas are confused, navigation by ocean
swells is difficult.
Winds
The direction of the
wind can be used to hold a course-the person steering simply holds
the wind at a constant bearing to the canoe. However, the wind may
change directions during the day (it is less stable than swells), so
the direction of the wind must be checked frequently against rising
or setting celesital bodies and the ocean swells. (See
Traditional Tahitian
Navigation.)
Landmarks
On coastal voyages, a
navigator can steer by landmarks. Lining up two landmarks (e.g. a
hill and a mountain) allows him to hold a straight line. Two pairs
of landmarks allow him to find a spot, such as a deep-sea fishing
ground, where the two lines intersect. One can also navigate by
knowing the shape of reefs or underwater topography which can be
seen from the surface. While leaving an island for the open ocean,
the navigator backsights on the island, lining up two landmarks to
hold his desired direction.
Seamarks
On the 1992 Hokule'a
voyage from Hawai'i to Tahiti, Mau Piailug shared with navigator
Shorty Bertelmann a seamark he had remembered from previous voyages
along the route: Mau told Shorty to look for a school of porpoises;
it would indicate that he had reached a point around 9 ° N latitude
on the route to Tahiti. Bertelmann sighted the porpoises at around 9
° N, confirming for him that he was on course and solidying his
faith in the traditions of Pacific navigation.
In Micronesia, these
living seamarks are called "aimers"and are "purported to be
associated with particular locales in the vicinity of islands or
midway between them. They comprise such things as a tan shark making
lazy movements, a ray with a red spot behind the eyes, a lone noisy
bird, a swimming swordfish, and so on. Each of these phenomena has
its own individual name and is located within a particular 'drag' on
a particular star course from its associated island. on the long
course from Puluwat to Eauripik there is said to be a row of whales,
each situated a day's sail directly south of an island. Each whale
has its own distinctive characteristic" (University of
Pennsylvania).
Grimble notes that
Gilbert Island navigators also have a tradition of seamarks: "As
Europeans use landmarks, so the Gilbertese [navigators] use seamarks
to check their daily position. These signposts in mid-ocean consist
of swarms of fish, flocks of birds, groups of driftwood, or
conditions of wave and skypeculiar to certain zones of the sea.
Hundreds of such traditional betia [seamarks] were stored up in the
race memory as a result of cumulative experience of generations"
(Grimble, Tungaru Traditions 48). These seamarks are found along
routes between islands and indicate to the navigator that he was at
a certain point along his route. For example, the seamark called
"the swarming of beasts" consisted of an extraordinary number of
sharks" and indicated the canoe was "a day's sail downwind of land."
Other marks include a region where flying fish leaped in pairs, a
zone of innumerable jellyfish, an area of numerous terns, an area of
sharks and numerous red-tailed tropic birds, a place marked by a
school of porpoises, a place where pairs of porpoises point their
heads "in the direction of the passage into Tarawa lagoon" (Tungaru
Traditions 49-50).
Signs of Landfall
Once the canoe is in
the vicinity of its destination according to the navigator's dead
reckoning and latitude measurements, the navigator starts looking
for land.
Navigating without
instruments is not a precise science. Poor weather and mental lapses
on a long voyage adversely affect its accuracy. But the navigator
need not sail to a destination with pinpoint accuracy to be
successful. Instead, the navigator in the Pacific tries to hit a
"screen" of islands, that is, a group of islands that stretches out
on either side of his destination. The longer or wider the screen,
the less likely the navigator will miss it. Islands in the Pacific
are seldom isolated; they are usually found in clusters. The Tuamotu
Archipelago stretches 550 miles north to south and 500 miles east to
west; the Society Islands stretches 160 miles north to south and 310
miles east to west; the Hawaiian islands extend more than a 1000
miles across the ocean east to west; the major islands form a
north-south screen of about 240 miles.
While sailing to
Tahiti from Hawai'i, the navigator can target a 400-mile wide screen
of islands between Manihi in the western Tuamotus, and Maupiti in
the eastern Society Islands. If the navigator can hit any one of the
islands in this target screen, he can reorient the canoe after he
identifies the island and determines its position in relationship to
his destination; if he does not recognize the island and the island
is inhabited, he can ask the islanders where he is and if possible,
get directions to his destination.
While there are
open-ocean gaps between islands in a screen, a navigator looks for
signs to let him know the proximity and direction of land even when
he cannot see it. Signs of land include drifting land vegetation;
clouds piled up over islands; the loom above an island created by
sunlight or moonlight reflecting up from the white sand and smooth
water of a lagoon; distinctive patterns of swells created by swells
refracting around and / or reflecting off islands; and seabirds.
Land-Based Seabirds
Seabirds such as the
manu-o-Ku (white tern) and the noio (noddy tern) go out to sea in
the morning to feed on fish and return to land at night to rest.
The diurnal flights of
such birds are the most useful signs for expanding landfall, since
their flights to and from an island gives a fairly specific
direction to the navigator. As the birds leave an island in the
morning, the navigator can sail in the direction the birds are
coming from to find land; as the birds rise up from fishing and
return to an island in the late afternoon, the navigator can follow
the birds to land.
During nesting season,
the habits of birds change. Nainoa Thompson tells this story about
his first voyage to Tahiti in 1980-2400 miles navigated without
instruments: "We saw two birds after the 29th day and I was
extremely relieved. At least we were in the ball park. The birds
rose up high and flew away, and we sailed in that direction; at
night we couldn't see the island so we took the sails down and
waited. The next morning, we looked for the birds to see what
direction they were coming from and that would be the direction of
the island. We waited for the first bird. All hands on deck. Not a
single bird. I began to worry-it was my first voyage, and I was
unsure of myself. Mau Piaulug was very calm and didn't say anything.
We waited and we waited. The canoe was just sitting in the water,
facing south. One of the canoe members was at the back of the canoe
and a bird flies right over his head. The night before that we saw
the birds flying south so how come late in the morning with the sun
very high was this bird coming out of the north? That would suggest
that we passed the island during the night. In my panic, I thought
we had better start sailing back in that direction to find the
island before the sun goes down again. We turned the canoe around.
But when I started to sail north Mau, who has always said that his
greatest honor would not be as a navigator but as a teacher, came to
me and said, "No." It was the first time that he interrupted the
trip. He said, "turn the canoe around and follow the bird." I was
really puzzled. I didn't know why. He didn't tell me why. But we
turned the canoe around and now we see other birds flying also. Mau
said, "you wait one hour and you will find the island you are
looking for." And after about an hour, Mau, who is about twenty
years older than me-my eyes are physically much more powerful than
his-he gets up on the rail of the canoe and says: "The island is
right there." And we all stood up and we climbed the mast and
everything and we just couldn't see it. Vision is not so much about
what you do-but how you do it. It's experience. Mau had seen in the
beak of the bird a little fish and he knew that the birds were
nesting. They had flown out to sea before sunrise and were taking
food back at mid-morning to feed their young, before they flew out
to sea again to feed themselves."
A low atoll with
coconut trees can be seen at sea from about 7 -10 miles away;
observing the daily flight patterns of seabirds can indicate the
direction of islands far out of the range of sight. Thompson gives
the following estimates of ranges of two seabirds that are the most
reliable indicators of land:
manu-o-Ku (fairy
tern): 120 miles (though this bird may stay out at sea, or fly
back to land unseen at night)
noio (noddy tern):
40 miles
Generally, sighting of
large groups of birds are more reliable signs of islands than one or
two birds stray birds or small groups. (See
How the Wayfinder Locates Land)
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