Report for Ka’elepulu Wetland,
1-16-05 to 3-26-05
January, February, and March in Ka’elepulu Wetland was a period when
much breeding activity was observed. Vegetation control efforts were conducted
on the islands until March when activity shifted to the edges of the moat.
The weather through the period continued to be wet and water levels fluctuated
widely. There has been no onset of hot dry weather yet.
Record keeping was standardized so that week to week comparisons of observations
can be made more easily. The format of this report reflects the standard
In January and February vegetation control work was conducted with the
goal of increasing stilt nesting areas. The crowns of the principal islands
were sprayed with 2% Aquasafe brand glyphosate herbicide. The intervals
between re-spraying were determined by the rate of regrowth of the alien
upland weeds that had formerly colonized the high parts of the islands.
The seed banks in the cleared areas were the source of recruitment after
Several new areas, completely dominated by Batus sp. were cleared during
this quarter. At the north end of the wetland a set of small islands and
depresions appear to remain from the original landscaping work when the
wetland was created. Some of these were restored.
The Batus was cleared generally by first spraying and then, when the leaves
have dropped, cutting them to ground level with a hand held weed whacker
fitted with a rotary or reciprical head. The volunteer help from Ron Walker
was invaluable in this work. Batus usually resprouted and was treated as
needed to prevent regrowth.
Several hundred mangrove seedlings were removed this quarter. Most of these
were small and recently rooted in the mud.
In March the USACE plan requires that work in nesting areas be suspended
for the protection of stilts eggs and chicks which are so cryptic that
they are easily trampled by workers. So after March 1st our work focussed
mostly upon vegetation management along the moat near the house site.
An area near the dock that was previously planted with native flora was
weeded and a thick ground cover of weidelia was cut. Replanting of some
areas with pohinahina was continued. The sedge Bulboshonus is being propagated
from seed for outplanting in potential galinule nesting areas. Seedlings
are being grown at the AML nursery at the manager’s residence.
Weed control efforts were also a part of the predator control work- reducing
habitat that might be used by rats and mongoose. An area of california
grass fringe, growing out into the water, was removed to eliminate bullfrog
habitat fronting island one.
Removal of the Pluchia sp. bushes at the water’s edge was begun.
Total eradication of pluchia from this wetland is a management goal. If
accomplished, re-seeding of the waterbird habitat can be prevented and
future management can be conducted more effectively.
Predator Control, Predation, and Hatchling Survival
Live trapping for rats, cats, and mongoose was conducted to control predation.
We recently became aware of the threat posed to stilt chicks by bullfrogs and
some control methods were attempted (although no trap or poison is known
to be effective in the control of these amphibians). We eliminated the vegetation
where they hide to ambush their prey in an area where their calling was heard.
On April 8th we tried to catch them by fishing for them with cane poles.
We caught none but they may have either been absent or unwilling to take
the bait at the time.
The Black Crowned Night Heron, Aku, is a native bird is known to prey upon
chicks in wetlands. Attacks upon feral ducklings have been witnessed by a neighbor
and aku are often observed stalking ducklings.
Eggs of feral ducks and geese were oiled to prevent hatching when nests are
located. Despite this preventative work, some nests were not found and eggs
did hatch out.
Of the half dozen or more broods of feral ducks known to have hatched in Ka’elepulu
Wetland, none have survived longer than a month.
Some hatchling ducks and coots may have died from exposure during heavy night
time rain storms or from disease but predation is possibly the biggest cause
of their disappearance. Bird watchers neighboring the marsh report that brood
size declines rapidly during the first week or two. Coot hatchling survival
is poor and may be similar to that of the mallards. Better counting is needed
to confirm this.
In March the owners and the manager attended a training seminar in predation
control. Live trapping of rats, cats, and mongoose will supplement control
with approved bait stations in the next quarter.
Trash and spray paint cans were collected semi-weekly during the quarter.
The edges of the habitat were surveyed for trash and mangrove seedlings
by canoe, usually on Mondays and often with the help of a volunteer neighboring
the wetland. Approximately two hundred spray paint cans were washed down
the stream into the wetland during the Spring. They are associated with
floating balls, are most common in the stream and near its mouth. They
probably come downstream from somewhere near the schools and culverts.
The rubbish collected is usually usually comprised of beverage containers.
These are most common along the makai shore of the wetland where winds
blow them into the paspalum fringe.
Species of Note:
Gallinule chicks were seen in March for the first time
this season. Stilts courted and mated this quarter. Coot and gallinule
nests with eggs were observed this quarter. In March an auditory count
of gallinules was made with a visiting biologist. Fourteen birds were
heard that day. This method is better for these cryptic birds.
Visiting migratory shorebirds were recorded in the marsh.
Mallards and geese were observed nesting this quarter. Their eggs were
treated with oil to prevent hatching when possible. No goose eggs
have hatched but
five or six clutches of mallards with up to a dozen ducklings each were
seen. No ducklings are known to survive longer than a month.
Mortality is probably mostly due to predation but dead ducklings
and coot chicks with no apparent cause of death are occasionally
found. They may
exposure during nights with heavy rainfall. Young downy ducklings that
become wet lose body heat rapidly when away from their parent during
The reason they became separated is not known.
Coot and gallinule nests with eggs were observed in February and March.
Their location and notes for each site are in Figure 2 below. Coot nests
flooded and their eggs drowned when water rose during rainy periods. Eggs
of one coot nest were found in the water nearby when there was no rising
These eggs may have been pushed out of the nest by competing birds.
On 3/21 four gallinule chicks were observed in the california grass fringe
by the mouth of the stream. Two of these chicks were observed on 4/15.
Although counts of nests and eggs are valuable, of greater value for management
purposes may be identification of the important nesting habitats or zones.
Coots preferred to nest very close to the water all around the islands. Gallinules
nested in the taller vegetation a bit farther away from the water near the
stream side of the marsh. Mallards generally hid their nests even farther
from the water under overhanging batus. The goose nest was high on a stream
in california grass in the shade of a tree.
Notably, nesting on the main part of Island One was not observed. This is
an area favored by the flock of feral geese. These large birds may reduce
in areas they frequent by invading nest sites and driving off females engaged
in nesting behavior.
After 3/1, regular inspection of nests on the islands was suspended per the
USACE instructions to stay away from nesting habitats. Nest observations
are more sporadic as a result. The number of nest sites found in March is
Figure 3, Known Nest Sites for 04-05 Season
C1- Rebuilt nest by pair flooded earlier on island one. Five eggs observed
C2- Rebuilt nest by pair flooded earlier on island three. This earlier
nest had one dead chick. On 2/7 two chicks had hatched and three eggs were
not yet hatched. No eggs were in nest on Friday so all probably hatched.
Parent on nest has a red spot on face shield.
C3- Rebuilt nest by pair flooded earlier. All four eggs hatched and chicks
were seen at the nest and elsewhere by Bill.
C4-New nest discovered two weeks ago, may not be active.
C5-New nest. Five eggs were observed on 2/12
C6-New nest site. No eggs observed.
C7- Nest site where two drowned eggs were found 3/21.
G1- Galinule nest with 6 eggs found 2/28
G2- Galinule nest with 2 eggs found 2/28
Goose- 16 eggs oiled on 2/21 and again 3/21
M- mallard nests since September