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No. 11
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| HAWAII'S WETLANDS |
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One of the richest areas for all types of wildlife is called wetlands. We sometimes call them by other names such as swamps, mud flats, marshes, moist soil, bottom lands and bogs; taro patches are also wetlands. In Hawaii, as streams flow to the ocean (as depicted in the drawing below) wetlands are created along the banks |
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| by the rise and fall of their water levels. Riparian (meaning on the banks of a river or lake) wetlands are very important to Hawaiian wildlife. For a better understanding of the word wetlands, we should note that it is compound--made up of two words--wet and land. This at first appears confusing; if something is wet, it is a river or stream or pond, but if it is dry it must be land! However, we must not forget that there is also land in between which is wet some of the time and dry at other times. Further, though some land may be permanently under water, it may be shallow and the land is merely a few inches below. Another definition of wetlands is a place where land and water meet. |
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HUMAN ACTIVITIES THREATEN THE WETLANDS Until very recent years the value of these places was not recognized; they were considered so worthless, in fact, that in many cases they were used for trash disposal. It was common |
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to make the land higher, permitting practice throughout the nation to dump soil, rubbish and junk cars into low lying areas for "fill" building and farming there. Hawaii wetlands often develop where mountain rain runoff is trapped by barriers such as sand dunes. Unfortunately, dredging, pumping and trenching easily modify these ponded areas. Some wetlands have been pumped completely dry. |
INCREASING AWARENESS OF WETLAND VALUES
These severe alterations to Hawaii's wetlands only gradually focused attention on the loss of a very important wildlife natural resource. Not until a few decades ago did scientists become fully aware of the problem. Along with this important knowledge came a better understanding of the incredible contributions the wetlands make.
FLOOD CONTROL FACTOR
Now we know wetlands absorb the destructive power of floods. The broad, flat areas along rivers and streams, swamps and bottom lands absorb much of the powerful effect of floods and trapped flood waters. These areas, far from being useless, are actually safety valves preventing destruction of property and loss of life caused by raging storm waters.
WILDLIFE NURSERY AREAS
Shallow, slow-moving water, thick aquatic vegetation and the abundance of dissolved nutrients make wetlands perhaps one of the most productive of the earth's environment. In low lying areas such as those along the coast of Hawaii, the rivers and streams mix with the ocean. The changing of tides, flow of the rivers and resulting mix of fresh and salt water creates a special environment called an estuary, in which many species of animals live, lay their eggs and feed their young. Wetlands slow the flow of water and the sun warms it as it moves through the shallows. The dissolved nutrients carried from the watershed increase the growth of microscopic plants and animals, which provide food for larger animals such as fish, insects and other invertebrates (animals without backbones) which often lay their eggs in this thick vegetation. Larger fish, birds and mammals are highly concentrated in and around wetlands, feeding on its rich resources. Wetlands are indeed wildlife "living museums!"
STOPS POLLUTION
During floods, large amounts of silt and other pollutants are carried downstream. In Hawaii, this runoff often kills the offshore reefs and pollutes the lower portions of rivers and streams. The biological action of wetlands breaks down these water-borne pollutants. Wetlands also capture flood-borne soil and mud, keeping coastal waters clear.
LOSING WETLANDS MEANS LOSING WILDLIFE
The loss of wetlands throughout our nation has been so great that only about 45 to 50% remain today. In Hawaii, because of the steep slope of interior mountains, agriculture and building of homes is confined to the narrow coastal strips. As a result, the impact on wetlands has been more severe. It has been estimated that less than 10% of Hawaii's former wetlands remain today. This loss has had a cumulative effect on four species of birds found only in our state: the Hawaiian coot, black-necked stilt, common moorhen and Hawaiian duck (koloa). These birds use the wetlands for feeding and nesting; wetland loss has caused a decline in their numbers. In 1970 these four were listed as endangered by the federal government, indicating scientists fear extinction of these birds if wetland destruction continues. Though endangered, some of these birds may still be found in our state wetlands. In addition to these endangered waterbirds, many other birds may also be found in Hawaii's wetlands: black-crowned night heron, cattle egret, Pacific golden plover. During the winter, it is possible to see up to 25 different types of North American waterbirds, ducks and geese which have flown here from the mainland.
ENDANGERED BIRDS OF HAWAII'S WETLANDS
HAWAIIAN COOT
The Hawaiian coot may be found on all main islands except Lanai. It is easy to identify by its dark plumage, distinct white beak and frontal shield. It is commonly found in open water such as reservoirs, streams, canals and estuaries. Coots feed on plants, small animals and insects. It is not uncommon to find several hundred coots gathering in large flocks when food is abundant. The nest is made from stems of grasses, sedges and other aquatic plants; it is bulky and tends to float, allowing it to rise and fall as water levels change. People often call this coot a mud hen because it may be seen feeding in mud flats. Hawaiians called it 'alae ke'o ke'o. Statewide population is estimated to be 1,400 birds.
HAWAIIAN DUCK
Often called by its Hawaiian name koloa, this duck was once found on all islands. With the exception of a few birds relocated to Oahu and Hawaii, this once abundant species is restricted to Kauai, where an estimated population of 500 to 1,000 is widely distributed. A sub-species of the N. American mallard, it is golden brown with orange feet and legs. The koloa utilizes both low elevation wetlands and mountain streams. Its nest is hidden in heavy cover and is lined with feathers. The bird lays two to 10 eggs, eats plants, insects and small animals of the wetlands. On Oahu the koloa has been known to mate with the related domestic mallard. Such interbreeding may cause the loss of this unique species over time.
COMMON MOORHEN
This bird, with its dark plumage and body shape, looks similar to the Hawaiian coot, but it can be identified easily by its bright red frontal shield. Unfortunately, this endangered bird is sometimes hard to see because it is very secretive and spends much of its time hiding in dense cover. The moorhen lives well in taro and lotus fields, where it moves under the thick canopy of leavers, feeding on aquatic plants and animals. During the morning and evenings, and during mating, the common moorhen often leaves its cover to feed in the open. It builds its nest of plant parts and mud in dense cover where it lays six to nine eggs. This bird is now found only on Kauai and Oahu. Specific population numbers are difficult to determine because of the bird's secretive nature. Estimates range from 600 to 900 birds The common moorhen is also known as the Hawaiian gallinule and, in Hawaiian, alae 'ula.
BLACK-NECKED STILT
A loud, sharp alert call, long, slender pink legs and black and white body quickly signify the stilt's presence for visitor's to the wetlands. The stilt has a liking for open shallows and mud flats where it uses its long beak to probe for fish, insects, crabs and other small animals. This bird nests in the spring, selecting open, barren flats where it lays four eggs in a slight depression in the ground. This is lined with a little debris, such as sticks and rocks. Immediately after hatching, the young move into heavy cover where they remain until they are ready to fly. Adult stilts often fake a broken wing to draw intruders away from their nest and the young. Present estimate of the number of black-necked stilts, called ae'o in Hawaiian, is 1,200.
LOSS OF WETLANDS CONTINUES TODAY
Loss of Hawaiian wetlands to urban development and agricultural methods indicated earlier in this discussion is still occurring. Many wetlands, for example, have dried up because their inflow waters have been diverted for agriculture or for drinking water or both! An additional technique of equally alarming disturbance to riparian habitats is that of channeling river and stream beds in many urban areas. As the large drawing below shows, this is a method of controlling occasional, but ever possible, flood waters in highly populated communities (residential and commercial) to protect properties from the heavy damage such flooding frequently inflicts. Channeling (with heavy concrete stream bed and bank walls) is practiced throughout the state. Note the difference this makes in the river environment compared to the pleasant natural surroundings illustrated in the scene on page 1. This shows why riparian wetlands are fast disappearing! The development, urbanization and farming problems posed to wildlife conservationists are, of course, extremely severe. But what is of additional concern to them is that the list of continuing threats (caused by both humans and uncontrolled animals) increases the challenge to achieving success in trying to slow down the rate of wetland loss. Some of the more serious threats are shown here and on the following page. Introduced barn owl and mongoose are very effective predators. Introduced plants such as water hyacinth, mangrove and several grasses and sedges invade and virtually choke the wetland, rendering it useless to most wildlife. Aggressive introduced fish such as talapia consume much of the available food in the wetland. Contaminants such as petroleum products, heavy metals and insecticides often drain into the wetlands, poisoning the inhabitants. Introduced cattle egret eats much of the food resource of the wetland, including the young of native birds.
OUTLOOK FOR CONSERVATION OF WETLANDS
IMPROVES THRU GREATER PUBLIC AWARENESS
A common management guideline notes that "understanding the problem
is the most important step in solving it." That approach has been
particularly effective in wildlife and conservation management. During
the last 25 years, growing awareness of the wetlands problem on the
part of the general public as well as governmental agencies has resulted
in giving it a very high ranking in environmental thinking. All changes
to wetlands are today carefully overseen and controlled by the federal
government. Further, the severe destructive activities such as dredging,
draining, filling, etc., are only allowed after a very complete study
of the project and steps are taken to create new wetlands to replace
those wetlands lost. Today anyone interested in helping preserve and
promote conservation efforts for the wetlands can make an important
contribution by getting to "understand the problem," and then
visiting one or another of the federal or state wetland reserves indicated
on the next page. Many groups are vitally interested in such conservation
work and may help add to your enthusiasm (Audubon Society, Boy Scouts
and Girl Scouts, Sierra Club, for example). After a century of neglect
and abuse, many wetlands are now being restored, with populations of
our endangered waterbirds stabilized! "Understanding the problem"
by visiting one of Hawaii's federal or state wetland reserves will not
only make you enthusiastic about protecting them, but it's great outdoor
fun doing it!
PUBLICLY-OWNED STATE & FEDERAL WETLANDS IN HAWAII
(Listed by island location)
Kaloko Pond ..............................................................................................................................Hawaii
Kanaha Pond State Wildlife Sanctuary .........................................................................................Maui
Kakahaia National Wildlife Refuge ..........................................................................................Molokai
James Campbell National Wildlife Refuge ....................................................................Kahuku,
Oahu
Nuu Pia Ponds Wetland Management Area (Kaneohe Marine Base) .........................................Oahu
Paiko Lagoon State Waterbird Sanctuary ....................................................................................Oahu
Pearl Harbor National Wildlife Refuge .........................................................................................Oahu
Hanalei National Wildlife Refuge ................................................................................................Kauai
Huleia National Wildlife Refuge ..................................................................................................Kauai
Mana Wetlands Waterbird Sanctuary .........................................................................................Kauai
LEARNING WETLAND WORDS
*Riparian describes an area along a _ _ _ _ _ _ _ _ _ .
*Estuary is a special environment where fresh river water mixes with _ _ _ _ _ _ __ _ .
*A practice called _ _ _ _ _ _ _ _ _ _ covers stream beds and banks with concrete to control flodding.
*Barn owls and mongooses are very effective _ _ _ _ _ _ _ _ _ .
*Invertabrates are animals _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ .
*Koloa is the Hawaiian name for the _ _ _ _ _ _ _ _ _ _ _ _ .
*The wetlands waterbird with long, slender pink legs is called the
_ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ .
*Getting to “ _ _ _ _ _ _ _ _ _ _ the _ _ _ _ _ _ _ “ involved in protecting our wetlands will make it easy for you to be enthusiatic about these wothwhile conservation programs!
*Answers to the word-questions above may be found on the pages of this
booklet.