Garnett's Galago (Otolemur garnettii)
The dental formula of this species 2:1:3:3 on both the upper and lower jaw (Ankel-Simons, 2000). Garnett's galago has a reflecting tapetum, all-rod retina, and an elongated fundus to assist in seeing during the night (Randolph, 1971). This species has a philtrum and a rhinarium (Ankel-Simons, 2000). This species has large apocrine glands located on the scrotal and circum-labial skin, lips, and the muzzle (Clark, 1978). This species has spines on the footpad that are prolongations of the stratum corneum and are glandless (Hager, 2001b). On the female, the vulva only opens during estrus (Tandy, 1974). During estrus of the female the scrotum of the male will enlarge slightly and a pink-colored patch of skin appears between the grooves of the two scrotal sacs (Tandy, 1974). The males' penis is 18 millimeters in length on average (Anderson, 1998). The penis has spines that are single and double headed and points towards the body (Anderson, 1998). Dixson (1989) found that the spines on the penis might also be triple headed. The penis spine pattern is uniform from base to tip (Anderson, 2000). The average body mass for an adult male is 794 grams and for the adult female it is 734 grams (Fleagle, 1999).
This species has four subspecies each having differing pelage colorations:
- Otolemur garnettii garnettii: The dorsal pelage coloration of this subspecies tends to be slightly greenish-toned reddish brown (Groves, 2001). The terminal half of the tail is black (Groves, 2001). The ventral side of this subspecies is yellow (Groves, 2001).
- Otolemur garnettii panganiensis: The last quarter of the tail of this subspecies is dark (Groves, 2001). This subspecies lacks the greenish tones found in other subspecies (Groves, 2001).
- Otolemur garnettii lasiotis: This subspecies is lighter and grayer than the subspecies Otolemur garnettii garnettii (Groves, 2001). The end of the tail is only slightly darker than the rest of the tail, and on the tip the color is usually white (Groves, 2001). The ventral sides of this subspecies are gray-white in color (Groves, 2001).
- Otolemur garnettii kikuyuensis: The dorsal sides of this subspecies are iron gray with a tinge of green, while the ventral sides are yellow-white (Groves, 2001). The tail is light brown, with the last quarter being black (Groves, 2001).
Garnett's galago is found in the countries of Somalia, Kenya, Tanzania, and on the islands of Zanzibar (Hager, 2001b). This species lives in highland and coastal forests (Hager, 2001b). This species also lives in riverine forests (Rowe, 1996).
This species has four subspecies each having their own range:
- Otolemur garnettii garnettii: This subspecies is restricted to Zanzibar and Pemba Islands (Groves, 2001).
- Otolemur garnettii panganiensis: This subspecies is found in the country of Tanzania from the Mozambique border north to Tanga, Mount Kilimanjaro, and Lake Manyara (Groves, 2001).
- Otolemur garnettii lasiotis: This subspecies is found from the Kenyan coast north to the Juba River in Somalia, and then south to Tanga in Tanzania (Groves, 2001). The range also extends inland to the Taita Hills and Kibwezi (Groves, 2001).
- Otolemur garnettii kikuyuensis: This subspecies is found in the Kenyan highlands east of the Rift Valley (Groves, 2001).
Garnett's galago is mainly a frugivorous species, that also consumes gum and insects. This species is more frugivorous than the related species Otolemur crassicaudatus (Nash and Harcourt, 1986). Masters et al., (1988) found that this species will consume mollusks. When presented with fish in captivity, individuals would fish them out of the water (Watson et al., 1994). This fishing behavior is thought to be a learned behavioral pattern because descendants of fishing parents were found to be the only individuals to successfully catch fish (Watson et al., 1994).
Harcourt and Nash (1986) found that the diet of this species in Kenya consists of 50% fruit and 50% animal matter. Fruits eaten by this species in Kenya include: Lannea stuhlmannii, Monanthotaxis fornicata, Uvaria acuminata, Grewia spp., Phyllanthus spp., Ficus spp., Meyna tetraphylla, Vitex strickeri, Harrisonia abyssinica, and Momordica trifoliolata (Harcourt and Nash, 1986). Coleopterans (beetles), Orthopterans (grasshoppers, crickets, cockroaches, and mantids), and Diplopodans (centipedes) are animals most consumed by this species in Kenya (Harcourt and Nash, 1986). This species was also found to consume snails (Gastropoda) and termites (Isoptera) in Kenya (Harcourt and Nash, 1986). Birds are also consumed by Garnett's galagos in Kenya based upon claws, skin, and feathers found in fecal samples (Harcourt and Nash, 1986). Birds consumed by this species may be the crested guinea fowl, Guttera pucherani (Harcourt and Nash, 1986).
Individuals will not cover the entirety of their home range within a single night, but rather concentrate usage on a specific area of the home range for a few nights, then move on to another part of their range and concentrate on that area (Nash and Harcourt, 1986). Males have home ranges that are 150-140% the size of females (Nash and Harcourt, 1986). Adults will sleep alone in this species, although the females will sleep with their young (Nash and Harcourt, 1986).
This species, unlike other galagines, moves quadrupedally through the forest and bush. When this species jumps, it lands with hindlimbs first (Harcourt and Nash, 1986). When it has to move on the ground in open spaces between the canopy, this species will hop (Harcourt and Nash, 1986). Garnett's galago was found to use supports 5 centimeters or more in diameter 54% of the time (Harcourt and Nash, 1986). This species uses horizontal supports the most (Harcourt and Nash, 1986). Individuals tend to move more when there is more moonlight (Nash, 1986).
This is a nocturnal species, with both sexes dispersing from the birth territory. Males will disperse farther and at a younger age than females, so male membership in a given population changes more than females (Nash and Harcourt, 1986). Males may disperse further than females so as to reduce the complications from inbreeding (Nash and Harcourt, 1986). Males and females have ranges that do not overlap with same-age individuals, but do share ranges with younger or older individuals (Nash and Harcourt, 1986). Males have home ranges that overlap one or more females (Nash and Harcourt, 1986). There are also transients in a given area who do not have a specific home range, where most of the transients tend to be males (Nash and Harcourt, 1986). Friendly interactions are found to occur at areas of range overlap between members of the same sex and members of the opposite sex (Nash and Harcourt, 1986). This species has a promiscuous mating system (Rowe, 1996). Garnett's galago shows a social network without the structure of a foraging group (Nash and Harcourt, 1986). Females are dominant in this species (Hager and Welker, 2001). Adult males were found to follow adult females more in captivity than females followed males (Hager and Welker, 2001). Females also in captivity were found to act aggressively towards novel males (Hager and Welker, 2001). This species is thought to be less social than the related Otolemur crassicaudatus because of its being more frugivorous, where it might be more profitable to exclude non-related same-sex individuals from the areas where fruits are available (Nash and Harcourt, 1986).
Social play in Garnett's galago consists of exaggerated walk, chasing, tail pulling, wrestling, non-aggressive biting, and pouncing (Price et al., 1999). In infants these play behavioral patterns are found on the first day of life (Price et al., 1999). Infants play more when they develop independence from their mothers during the fourth and fifth weeks of life (Price et al., 1999).
Head cocking was found to be a behavior that is associated with visual investigation in response to a novel object (Cantalupo and Ward, 1998). Head cocking is described as "a rotating movement of the head around its rostro-caudal axis while orienting in a fixed direction" (Cantalupo and Ward, 1998). Head cocking occurs more in juveniles than in adults (Cantalupo and Ward, 1998; Cantalupo et al., 2002). Head cocking was found to occur more with animal stimuli than with inanimate objects (Cantalupo et al., 2002).
raucous cry call: This call is only emitted by males and is given with the individual stationary and the mouth slightly open (Tandy, 1976). Clark (1988), however, observed that both males and females emitted this call in captivity. This is a multisyllabic call that rises to a crescendo on the second or third note, and then fades away in the last notes (Nash, 1986). The individual notes sound like the "caw" of a crow, and some notes have a "warbling" quality (Nash, 1986). The duration of this call ranges from 4-5 seconds (Nash, 1986). This call can carry for 400 or more meters (Nash, 1986). The frequency range of this call is from 40-4000 hertz (Masters, 1991). This call is described as being more melodious as compared to the same call uttered by Otolemur crassicaudatus (Masters, 1991). It utters the call from tall trees and the body shakes rapidly while emitting the call (Estes, 1991). These calls can be used by researchers to distinguish individuals from one another (Estes, 1991). This call is uttered most often during the mating season (Estes, 1991). Often this call is responded to by conspecifics with the same call, and two or several individuals may form a chorus emitted this call (Nash, 1986). This call could also function as a spatial indicator (Tandy, 1976). On Zanzibar, this call is heard at a constant level throughout the night (Lumsden, 1995).
alarm call: this call can take the form of the following number of noises: rattle, moan, chatter, chirp, whistle-yap, whistle, squawk, creak, knock, and sniff (Estes, 1991). These calls can last for up to an hour (Estes, 1991).
distress call: this call sounds like a yell (Estes, 1991). This is high-pitched and given in response to pain or fear (Estes, 1991). This call not only attracts other Garnett's galagos, but also potential predators (Estes, 1991).
infant click call: like the other galagines, this clicking type call sounds like "tsic" (Estes, 1991; Becker et al., 1998). The infant emits this to elicit contact from its mother (Estes, 1991). Mothers will respond to this with short growl call (Becker et al., 1999). This call appears in the first weeks of life (Becker et al., 1998).
infant growl call: This call is emitted after the infant falls or misses a landing (Becker et al., 1998).
infant humming call: This pulsating type of call is emitted while the infant is being groomed by the mother (Becker et al., 1998).
short growl call: This call is emitted by mothers in response to the infant "tsic" call (Estes, 1991). The call sounds like "growl", and can occur alone, or with other growls, or in succession with the infant click call (Becker et al., 1999). This call lasts less than one second (Becker et al., 1999). This call would result in nurturing behavioral patterns (Becker et al., 1999).
long growl call: This call is emitted by mothers in response to a threat from the environment (Becker et al., 1999). This call will last more than one second (Becker et al., 1999).
sex call: This call, emitted only by the male, is given before and after grooming (Estes, 1991). This call is low frequency and sounds like a crack call (Estes, 1991). The call ranges from "clicks" that have a high frequency and grating sounds that have a low frequency (Tandy, 1976).
foot-rubbing: This is when an individual will rub, or scrape, the foot against a piece of wood or another substrate (Hager, 2001a, b). The area on the foot that is used has extensive horn-like structures and skin that is much tougher than surrounding skin on the foot (Hager, 2001a, b). The substrate is scraped for 2-5 seconds for varying intensities (Hager, 2001b). Both feet are used when performing this behavior, but only one at a time (Hager, 2001b). This scraping action will produce a noise that is indistinguishable to other background noises, and this may mean that this behavior is used for communication amongst conspecifics without revealing the position to potential predators (Hager, 2001a, b). Males will perform this behavior more than females, but females do possess the horny structures and tough skin on the foot like the males (Hager, 2001a, b). Males and females will perform this behavior during agonistic encounters (Hager, 2001a, b). Females will also perform this after being approached by males (Hager, 2001a, b). Males will also perform this when following females and in a response to other male foot-rubbing (Hager, 2001a, b). Tandy (1974) reports that this behavior is sometimes accompanied by urination or urine-washing, but Hager (2001b) reports that neither urination or urine-washing occurs with this behavior. Although this behavior is done by the foot, it is included here because sound is the production of this behavior.
cheek rubbing: This is when an individual will rub the cheek region against a support (Tandy, 1976).
chest-gland marking: this is behavior is done by both adult male and female Garnett's galagos (Estes, 1991). The gland on the chest is rubbed against tree trunks and branches (Estes, 1991). This is a highly stereotyped behavior with Garnett's galago rubbing its chest in hard to reach areas of the trees (Estes, 1991). Its function is marking of a territory, and the dominant males do this most frequently (Estes, 1991).
ano-genital rubbing: This is when an individual will drag the ano-genital region across the substrate (Tandy, 1976).
urine-washing: Garnett's galago takes its hands and cups them, and then deposits urine on them (Estes, 1991). Next Garnett's galago takes that urine and spreads it on the soles of the feet (Estes, 1991). When Garnett's galago walks now, it leaves a little bit of urine on the substrate (Estes, 1991). Males urine-wash more frequently than females do, and when the female is in estrus, the male will deposit the urine directly upon the female, but all age classes perform this behavior (Estes, 1991). A Garnett's galago will urine-wash when foraging in a new area, looking at a strange object, during aggressive encounters, and social grooming (Estes, 1991). This behavior occurs more frequently in dominant individuals (Tandy, 1976).
rhythmic urination: Garnett's galago does this when it is in a new area (Estes, 1991). It moves slowly while depositing a small amount of urine on the substrate (Estes, 1991). This behavior is performed more frequently by female Garnett's galagos than it is by males (Estes, 1991).
ano-genital muzzle: This is when one individual will sniff the anal-genital region below the base of the tail of another conspecific (Tandy, 1976).
sniff: This is when one individual smells the area around another (Tandy, 1976).
defensive attack posture: Garnett's galago does this when threatened into a corner (Estes, 1991). It stands on its hindfeet with the arms in an outstretched position, with the hands cupped; it tends to look like a boxer (Estes, 1991). This behavior may be accompanied by cuffs and bites (Tandy, 1974).
mouth-open display: This is when the mouth is slightly open and there is no sounds emitted (Tandy, 1976). During this display the teeth may or not show (Tandy, 1976).
avoid: This is when an individual moves out of the way of an approaching conspecific (Tandy, 1976).
crouch: This is when an individual will bend low towards the substrate and has all of the limbs flexed (Tandy, 1976).
tucked-under tail: This is when an individual will tuck the tail under the body and it serves to communicate submission (Sauer and Sauer, 1963; cited in Tandy, 1976).
nose-to-nose sniffing: Garnett's galago does this when first coming upon a conspecific (Estes, 1991). This is followed by nose-to-face contact (Estes, 1991).
nose-to-face contact: this occurs after nose-to-nose sniffing (Estes, 1991). An individual will touch the face of a conspecific with its nose (Estes, 1991).
social grooming: this behavior is not as developed in Garnett's galago (Estes, 1991). This behavior is basically regulated to reciprocal licking (Estes, 1991). Males mainly groom females (Tandy, 1974).
cuff: This is when an individual will slap another conspecific with the hand (Tandy, 1974). The mouth may be held open, the arms may be raised, and the individual may be in a bipedal stance when performing this behavior (Tandy, 1974). The individual may also remain sitting with the mouth slightly open when performing this behavior (Tandy, 1974). This behavior serves to communicate aggressiveness on the part of the sender (Tandy, 1974).
The gestation of Garnett's galago is about 126-136 days (Manley, 1966; Eaglen and Simons, 1980; cited in Nash, 1983). This species gives birth once a year between August and October, when vegetation is thick (Nash, 1983; Nash and Harcourt, 1986). Although in captivity it has been reported that this species has continuous estrus cycles, thus being able to give birth all year and not have a birth season (Eaton et al., 1973; Izard and Simons, 1986; both cited in Masters et al., 1988). Nests are made in the tangles of vegetation (Nash, 1983). One infant is born at a time for this species with twins being rare (Nash, 1983; Nash and Harcourt, 1986; Masters et al., 1988). Infanticide has been reported in captivity (Tandy, 1974). Young are weaned at the beginning of the driest season (Nash, 1983). Mothers will transport their young in their mouths and park them when foraging (Welker and Schafer-Witt, 1988; Rowe, 1996). Infants become independent from their mothers between the fourth and fifth weeks of life (Price et al., 1999). Both sexes reach maturity at about 20 months of age (Nash and Harcourt, 1986).
A typical sexual encounter occurs as follows: first the male licks the genitalia of the female and then emits sex call (Tandy, 1974). If the female is receptive she will move into the copulatory position, with the rump facing the male (Tandy, 1974). The male will mount the female from behind and thrust after insertion (Tandy, 1974). The male may dismount and then remount after licking the head of the female (Tandy, 1974).
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Last Updated: April 1, 2007.
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