Opened Shell Showing The Paradise Nuts
The bats is natured dispersal of trees and plants by known as chiropterochory, and the bats of the family Phyllostomidae are the principle agents in the American tropics. This paper report the food preference of the greater spearnosed bat, Phyllostomus hastatus hastatus (Pallas), for the seed attachment of the sapucaia nut or paradise nut, Lecythis zabucajo Aubl., in Trinidad and discusses the hitherto unknown synzooic relationship between this bat and the dispersal of the nut.
Because the edible sapucaia nut has a flavor considered superior to that of the Brazil nut (Bertholletia excelsa), to which it is closely related, the tall spreading sapucaia tree of commerce, found primarily in the Amazon forest, was introduced into Trinidad around 1900 and planted in groves on estates, with a view to its development as a commercial crop for confectionery, cooking oil and table purposes (Williams and Williams, 1951).
In this respect it has been a failure, since few nuts can be marketed as the annual crop is usually depleted by bats. However, I have been informed by some residents that wild forest trees of this species have increased. Most of the Brazilian species of Lecythis are known as “sapucaia”, the Tupa Indian word for hen . The trees are found along waterways and though not numerous are a conspicuous feature of the forest because of their large size. The bark is used for tanning and supplies material for oakum, cigarette paper and tinder.
The sap is said to make a refreshing drink. The large woody fruit shells, which contain the nuts, are used for ornamental and various domestic purposes such as water vessels (Record and Hess, 1943] Sometimes the large pods are called “monkey pots” because they are baited with sugar and used to trap monkeys which cannnot withdraw their head when inserted (Kennard and Winters, 1960).
The nuts are a valuable article of food and yield about 40 percent of oil suitable for cooking and domestic purposes. Although there are a few small plantations on the alluvial areas of the lower Amazon River, the nuts are nowhere cultivated and most are collected from scattered forest trees, whale many fall to the ground and are eaten by wild animals.
Huber (1909) stated that in Brazil, fruit bats were the most important agents for seed dispersal in the Amazonian forests and mentioned three categories of plants that are particularly adapted for dissemination by bats, none of which included Lecythis. He also stated that monkeys are the principal disseminators of Lecythis since they like the odor and taste of the nuts, while rodents are next, especially agoutis (Dasyprocta), which feed upon fallen nuts. The first reference found mentioning any relationship between bats and the sapucaia nut stated that “fruit-dating bats attack it” (Campbell, 1957) and that this occurred in Trinidad.
Paradise Nut Tree
The only other reference was Goodwin and Greenhall (1961) who reported that, in Tri- nidad, the large frugi-carnivorous Phyllostomus hastatus hastatus had a predilection for the nuts. Neither Campbell nor Goodwin and Greenhall mentioned whether Lecythis is a food specifically attractive to bats or simply a food which is incidentally eaten by bats.
Van der Pijl (1957) in his studies of the dispersal of plants by bats stated: “It is possible to recognize a typical bat fruit, even if it were only because transport by other agents appears to be excluded.” He listed a number of characteristics which distinguish between bat fruits and those Primarily attractive an dispersed by such arboreal mammals as monkeys and squirrels or those dispersed by birds. Bat fruit characteristics are:
- edible part soft or hard,
- dimensions of fruit and seed large, up to those of a mango,
- dull color,
- unfresh odor,
- attached to the tree till after maturity,
- possibly tough skin (indehiscence),
- exposure outside the foliage, viz.
- at the end of the branches,
- on the outside of the crown,
- inside a very loose crown, dangling on long, slack stalks (flagilliflory) or,
- attached to the main branches and the trunk (cauliflory).
The sapucaia qualifies as a typical bat fruit when Van der Pijl’s criteria are applied to botanical descriptions of the fruit and seeds following Kennard and Winters (1960) and Record and Hess (1943). The following italics are mine and refer to the special characters listed by Van der Pijl. The nuts are brown, oblong, ridged and about two inches long. They are enclosed in a heavy, large, brownish urn-like jruit or pod about eight inches long and ten inches wide, which from its weight, naturally hangs in an inverted position at the end of the branch (Fig. 1).
This thick, woody pod has a large terminal lid, which becomes detached and falls off when the fruit matures (Fig. 2),
leaving the numerous nuts exposed and dangling within a circular chamber having a four-to five-inch opening. Each nut is attached to the fruit by a fleshy stalk or funiculus which eventually dries up or rots and finally breaks, allowing the nut to fall (Fig. 3).
However, in Trinidad, few nuts drop to the ground. A musty, fetid odor (caused by the rotting stalks) pervades a tree with ripening fruit.
I observed that when the first fruits ripen in late November and early December, each evening about dusk a great many —perhaps a hundred— large, screeching bats would enter the Sapucaia groves, wheeling about, under and over the foliage. Other much smaller bats on the wing quickly seemed to leave the vicinity (Goodwin and Greenhall, 1961:240).
Spear-Nose Bats
I believe that the bats are attracted by the smell of the decomposing funiculi of the nuts, Most of the fruits were exposed outside the foliage at the end of the branches and easily accessible to the bats which did not have to fly in and out of the dense foliage. A single bat would fly to a pod, close its wings, and attempt to enter the fruit-opening, head first. Once inside the fruit, the bat removed a nut neatly biting away its fleshy funiculus; then the bat simply dropped from the pod, feet first, and flew off with its booty.
Immediately mother bat followed and repeated the process, until all the ripe fruits whose lids had dropped during the day were now oompletely emptied of nuts. The mass visitation lasted for about 15 to 20 minutes, terminating shortly before dark. The bats then silently flew off, without screeching, to return at dusk the following evening. Bats visited several groves under observation including a few individual trees (originally planted as ornamentals), for several weeks until all pods had been emptied.
It is the fleshy attachment of the nut which is eaten by the bat. In order to secure this item, the bat must remove the nut with its funiculus and it is this device, in my opinion, which insures chiropterochory. It is probable that the bat separates the funiculus from the nut in flight, dropping the nut over the forest, thus completing the seed dispersal of Lecythis.
I have seen some undamaged sapucaia nuts at the roost bases of Phyllostomus hastatus hastatus. Nuts were never observed under the roosts of either Artibeus jamaicensis trinitatis or A. lituratus palmarum, the only other Trinidad fruit bats large enough to carry the nut and its attachment. Neither have other bats, monkeys, squirrels, nor any birds been observed to feed upon the seeds in Trinidad, although it is possible that ground mammals, such as agoutis, paca, peccary and deer, might feed upon fallen nuts.
It has not yet been determined whether Phyllostomus hastatus hastatus disperses the sapucaia nut of commerce in South America, but from the observations in Trinidad, it is probable that it does play a similar role. This could be readily determined by careful observations made during a single fruiting period of the tree in the Guianas or Brazil.
It is interesting to note that both bat and tree have almost identical ranges, with the species Phyllostomus hastatus found from Honduras through southern Brazil (Cabrera, 1957) and the various species of Lecythis widely distributed from southeastern Brazil through northern South America to Costa Rica (Record and Hess, 1943).
Author:
ARTHUR M . GR E E N H A L L
LITERATURE CITED:
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CAM PBEL L, J. S. 1957. Some observations on the fruit trees of Trinidad. J. Agr. Sot. Trinidad and Tobago, 57 (2): 209-223.
DEAN, R. E. 1937. Guide to the Royal Botanic Gardens Trinidad. Dept. Agr. Trinidad and Tobago, 46 pp.
GOODW I N, G. G., AND A. M. GREENHALL . 1961. A review of the bats of Trinidad and Tobago. Bull. Amer. Mus. Nat. Hist., 122 (3): 187-302.
HUBER, J. 1909. Mattas e madeiras Amazonicas. Bol. Museu Goeldi (Para-Belem), 6: 91-225.
KENNARD , W. C., AND H. F. WINTERS. 1960. Some fruits and nuts for the tropics. U. S. Dept. Agr., Misc. Pub. No. 801, 135 pp.
RECOR D, S. J., AND R. W. HESS. 1943. Timbers of the New World. Yale University Press, New Haven, 640 pp.
VAN DER PIJL, L. 1957. The dispersal of plants by bats (chiropterochory). Acta Botanica Neerlandica, 6: 291-315.
WILLIAMS , R. O., AND R. O. WILLIAMS , JR. 1951. The useful and ornamental plants in Trinidad and Tobago. 4th Ed. Trinidad and Tobago, 335 pp.
