Unique Ecology

Unique Ecology

The importance of columnar cacti to Curacao’s culture and nature

By Dr. Sophie Petit, University of South Australia and CARMABI

Biology of the cacti:

Biology of the cactiCacti occur mainly on the American continent. Curacao has three species of columnar cacti: datu (Stenocereus griseus), kadushi (Subpilocereus repandus) and kadushi di pushi (Pilosocereus lanuginosus).
All three species produce flowers, each of which opens for only one night, during the dry season, when most other native plants appears dry and even dead.
They are thus extremely important to Curacao’s native wildlife because they provide them with vital resources.

A lot of research has been done on datu and kadushi, which are the most abundant of the three species.
They are self-incompatible, which means that the female part of each flower must be pollinated with pollen coming from another plant.  Only animals can perform this service.
In fact, nectar-feeding bats are responsible for all of the pollination of datu and 90% of the pollination of kadushi.

Kadushi flowers sometimes stay open for a few hours after sunrise and may be visited by birds such as hummingbirds. Without the bats, however, there would be very few cactus fruits and seeds, and the cacti could not reproduce sexually.

Cacti grow very slowly.  The very large cacti are certainly several hundred years old.  They are particularly important to wildlife because they start producing flowers earlier in the season than do small cacti, and make the link between seasons of abundance, filling gaps when few resources are available.

The three species have different behaviours when it rains: datu stops flowering, kadushi continues to flower, and kadushi di pushi start flowering very rapidly.  So at all times of the year, large cacti take care of our wildlife.

Importance of columnar cacti to nature:

Cacti provide fruits and flowers to a range of animals including many species of birds, two species of bats, iguanas, and many species of insects such as bees.  They are able to survive in the natural environment without artificial watering, and datu and kadushi produce most of their flowers and fruits during the dry season, when very few other resources are available for our wildlife.

The flowers contain large amounts of nectar and the fruits are rich in water.  Our precious nectar-feeding bats, Leptonycteris curasoae curasoae (which of course gets its name from Curacao) and Glossophaga longirostris elongata (also a Curacao native) are very important in the pollination of many significant Curacao plants, and they depend on columnar cacti for their survival.  The very large majority of their diet consists of cactus nectar, pollen, and fruits when they can get them. Without the cacti these bats could not survive on Curacao.

The branches of the cacti are also filled with water, which is used by several animals including prikichi and the white-tailed deer.  Within the branches, birds make their nests, iguanas rest, and other animals find some respite.  Birds perch on their branches.  For example the warawara often examines the surroundings by perching on cacti.

The shade of the cacti is very important to animals, but also to other plant species.  Cacti often act as “nurse plants” in hot climates, meaning that their shade, and sometimes nutrients associated with their presence, help seedlings of other species to become established, which they may not be able to do when the soil is hot or poor.  The regular dropping of cactus branches insures that soil will be produced, and soil is a rare commodity on Curacao.

Cultural significance of cacti:

Curacaoans’ ancestors enjoyed the delicious dense and breezy shade of columnar cacti, and some of us enjoy it still today, if only for parking our car.
A few people still make the famous kadushi soup, renowned to give plenty of energy to those who eat it.
But the grandparents and great-grandparents of Curacaoans also used cacti for many other things: door and window frames, rope, beds, boxes, torches, utensils, shampoo, and medicines were made with kadushi; syrup was made with datu fruits; hedges made of datu can still be seen in some places and are determining elements of the typical kunuku landscape (Rojer-Beenhakker 1990), and datu also had numerous medicinal uses (see “Green remedies and golden customs of our ancestors”, by D. Veeris, Triangel Publicaties, 1999).

Cacti were of vital importance to Curacaoans and the few large cacti that remain today were the very cacti that were used and appreciated by the great great-grandparents of today’s Curacaoans.

Conservation issues:

Unfortunately, there is no legal protection currently for cacti.  Urban development projects sometimes leave a few cacti standing, but the people who purchase the blocks of land then cut down the cacti.

Goats eat the seedlings, and birds eat the fruits before they are ripe, thus causing a major crisis in the recruitment of young cacti.  An unknown disease has been affecting kadushi, and the prikichi put a lot of pressure on the trees by grazing the branches.

Because they are keepers of Curacao’s biodiversity, cacti must not disappear. Where they are eliminated, biodiversity crashes.  This biodiversity is important not only for cultural and ecological reasons, but also financial ones via tourism and the health of ecosystems.
Large areas of cacti have disappeared in the last 20 years.

What can we do?

On lease agreements for rental properties, vegetation clearance should not be permitted. Also, the protection of significant vegetation should be included in the legislation.

An education campaign for the people of Curacao should show that columnar cacti are the jewels of Curacao; they gave life to our ancestors and to our wildlife. They are extremely slow growing and should be preserved at all costs, including in urban gardens.

One established cactus is very precious and will never require watering.  Please pass the word: columnar cacti are very important to Curacao!

The importance of bats to Curacao!

Biology of the bats:

Biology of the batsEight species of bats occur on Curacao.
All are from the sub-order Microchiroptera; flying foxes do not occur on the American continent.

The bats of Curacao belong to three ecological groups: insectivorous bats, nectar-feeding bats, and one species of fishing bat.  Most bats live in caves and crevices, although some may also use tree roosts. In addition, two species have been observed in buildings on the island; others may occasionally use buildings as well.

Sick bats, like any other sick wild animal, should not be handled, but bats do not attack people.

They forage at night using their vision, smell, and a wonderful sonar system called echolocation. We cannot hear the sounds they make because the range of frequencies is not audible to humans; the sounds are reflected on surfaces obstacles, prey such as mosquitoes); bats hear them and can find their way even in total darkness.

Our bats have only one young (pup) per year; because they are mammals, others feed their pups milk until the young are old enough to forage on their own. Family ties may remain strong even after the young become independent.

Most species are very sensitive to disturbance, and they consist of only a few dozen or a few hundred individuals on the island. Bats are also affected by pollution and the removal of vegetation.

Importance of bats to Curacao:

Insectivorous bats include Mormoops megalophylla intermedia (the ghost-faced bat), Natalus tumidirostris (the funneleared bat), Molossus molossus pygmaeus (the velvety free-tailed bat or Pallas’s mastiff bat), Myotis nesopolus nesopolus (Curacao Myotis), and Pteronotus davyii (the naked-back bat). None of the populations is larger than a few  hundred individuals, yet these insectivorous bats are very important to Curacao.

They capture insect pests such as flies, mosquitoes, and certain moths that are agricultural  pests. Certain bat species can capture their own weight in insects each night and eat several hundred small insects in one hour. Although the heaviest of those bats weighs less than 30 g, each bat still represents the elimination of a significant number of pests.

The species most likely to be found in a building is Molossus; one specimen was hit by a car in 2007, the only one seen in years. If a roost is found, please contact CARMABI; the bat’s special feature is to have a tail.

Curacao has two species of nectar-feeding bats, belonging to the group of leaf-nosed bats: Glossophaga longirostris elongata (long-tongued bat) and Leptonycteris curasoae curasoae (long-nosed bat), which gets its name from the island. These bats also consume ripe fruits when they are available and disperse the seeds when the seeds are small enough to be ingested.

Their role in the pollination of plants of significance, such as Datu and Kadushi, but also the Calabash tree and Agaves, among others, make them vital contributors to biodiversity on Curacao. By allowing the formation of fruits on Datu and Kadushi, the bats make accessible resources that many animals use during the dry season.

Only Glossophaga is found in buildings.
Leptonycteris has strict hot cave requirements and is also very shy.

The fishing bat, Noctilio leporinus (greater bulldog bat), is the largest on the island, weighing about 60 g. Its feeding techniques are remarkable and well worth observing: it captures small fish at the surface of the water using echolocation; it also eats insects in flight and other terrestrial animals like small crabs and scorpions. The bat’s ecological functions include the creation of a habitat for other creatures in its coastal roosts.

Artibeus jamaicensis, a fruiteating bat, has not been seen since 1947 on Curacao. It is likely that the two specimens captured were vagrant and that the species no longer occurs on the island.

Conservation issues:

Bats constitute the largest native group of mammals by number of species for Curacao, but their distribution and numbers have been declining over the last century. Based on their physical characteristics, several subspecies have been determined to be endemic to Curaçao (they occur only here). We are left with a few hundred individuals for the most abundant species; such low numbers are very alarming and the risk of extinction is not only real, but high. Bats are extremely sensitive to pesticides and other forms of pollution, so that contaminated insects or other food sources may poison them. Roost disturbance is also likely to be a factor affecting the survival of bats; bats have tiny stores of energy and disturbances not only stress them out but also deplete their energy. Critically, the removal of native vegetation is very detrimental to bats. Not only are tree roosts destroyed, but the habitat in which specific insects live is destroyed as well. Finally, the destruction of cacti affects not only the general biodiversity of Curaçao, but also Glossophaga and Leptonycteris, bats that depend on the nectar of cactus flowers for survival.

What can we do?

If bats must be removed from a building, it is necessary to give them the opportunity to leave during the night. Blocking all bat entrances should be done at night, when all bats are gone, and at a time when pups are not present.

Information is available at: http://batcall.csu.edu.au/abs/absmain.htm and http://www.batcon.org/home/index.asp?idPage=51&idSubPage=47; the eviction may take a little patience.

Exclusion should use a one-way device that allows the bats to leave but not to re-enter. Other methods are not ethical and will cause stress and pain to the bats, and are also likely to kill many. It has been reported that wind chimes placed at night in the buildings may encourage the bats to find another place to live.

It is important to promote the retention of the native vegetation of Curacao and to minimize disturbance to caves and other roosting sites. Bats are very precious to Curacao and responsible for many good deeds, from which we benefit.

Public education about bats is everyone’s responsibility; when you know, pass it on. The legal protection of bats should also be supported.

Students interested in making a presentation about the bats of Curacao can get informationsheets in Dutch by emailing info@carmabi.org.

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