Saguinus illigeri

29.

Ilhiger’s Saddle-back Tamarin

Saguinus illigeri

French: Tamarin d'llliger / German: Schwarzkopftamarin / Spanish: Tamarin de llliger

Taxonomy. Hapale illiger: Pucheran, 1845,

type locality unknown. Restricted by P. Hershkovitz in 1996 to the left bank ofthe lower rio Ucayali, near its mouth, Loreto, Peru.

Formerly considered a subspecies of S. fuscicollis. Intergradation between S. illigeri and S. leucogenys has recently been discovered in the San Martin area in Moyobamba and the Rio MayoValley, and the resemblance of these two species is more apparent there than along the Rio Ucayali and Rio Tapiche. This similarity between the phenotypes was mirrored in the mitochondrial data, with S. leucogenys forming a well-supported clade with S. illigeri in the northern part ofthe former’s distribution. Monotypic.

Distribution. E Peru, between the rios Huallaga and Ucayali, S of the Rio Maranon, and E of the Rio Ucayali, from the mouth of the Rio Blanco and along the left bank ofthe Rio Tapiche.

Descriptive notes. Head-body ¢.20 cm, tail ¢.31 cm; weight mean 293 g (n = 14). IIliger’s Saddle-back Tamarin has a black forehead and crown and a blackish throat. The mantle and outer sides of arms are chestnut. The facial skin is black, with short gray hairs surrounding the mouth and nostrils. The mantle is short, extending only just beyond the shoulders. The saddle is marbled black and gray or buffy to ocherous. Rump and thighs are reddish orange, and upper surfaces of the hands and feet are black, often mixed with reddish. The chest, belly, and innersides of limbs are reddish. The tail is black except for a short reddish part extending onto the rump. External genitalia are mostly or entirely black.

Habitat. Primary and secondary lowland rainforest and seasonally flooded varzea forest. Illiger’s Saddle-back Tamarin prefers dense vegetation in secondary forest and tree falls. Demography, daily activities, movements, diet, and habitat use were studied intermittently between 1979 and 1984 by P. Soini at a site on the 4-3-km? fluvial island of Cahuana, in an ox-bow lake ofthe Rio Pacaya in Pacaya-Samiria National Reserve in north-eastern Peru.

Food and Feeding. Diets of Illiger’s Saddle-back Tamarin include mainly fruits, plant exudates (gums and nectar), arthropods, frogs and lizards, some flowers, leat buds, and honey. Soini recorded his study group eating fruits from nearly 60 plant species, and fruits were the main food resource in all months of the year except September in the peak ofthe dry season when gums were important. Nectar was also consumed in relatively large quantities (13% ofthe diet) in the early dry season, notably from the vine Combretum fruticosum (Combretaceae). For nearly all fruits, the succulent or viscid mesocarp or aril was eaten. In the early wet season, fruits of Cordia ule: (Boraginaceae) and Ficus (Moraceae) were important; in the middle ofthe wet season, Tapirira guianensis (Anacardiaceae), Inga mathewsiana (Fabaceae), Pourouma (Urticaceae), and Celtis iguanaea (Ulmaceae); and in the late wet season, Brosimum rubescens (Moraceae), Inga, and Celtis. The major resource species were used intensively during their fruiting periods, and in all but one of the 13 months of Soini’s study, just 1-2 species accounted for more than 70% of the plant parts of the diet in each month. Fruits ofthe liana Odontocarya tripetala (Menispermaceae) were important in the dry season, but gums were a larger component ofthe diet at this time when fruits were scarce. Thirteen plants supplied gums, including gum that exuded abundantly from seed pods ofthe leguminous tree, Parkia oppositifolia. Other gum sources arose from abrasion and windstorm injuries, insect perforations, and holes gouged by squirrels or other rodents on the bark of trees and woody vines. Gums of Parkia oppositifolia (Fabaceae), an unknown legiminous tree, Spondias mombin (Anacardiaceae), and Lonchocarpus glabrescens (Fabaceae) were most important in the dry season. After eating readily available gum, Illiger’s Saddle-back Tamarin often bit and chewed small pieces ofbark, although this behavior was not comparable to the specialized tree-gouging of the marmosets. Animal prey included grasshoppers and other orthopterans, cicadas (important in January-February when they emerged), butterflies, moths, larvae, spiders, frogs, and lizards (mainly Gonatodes humeralis and Anolis fuscoauratus). Their predominant form of foraging for hidden animal prey involved a manipulative search in cavities, tree holes, and specific sites in the lowest levels of the forest; 67% of their foraging time was in the shrub stratum below 5 m above ground. Occasionally, they drank by dipping a hand into a tree cavity containing water, and then licking it; sometimes they licked moist surfaces of leaves.

Breeding. At Cahuana, births of Illiger’s Saddle-back Tamarins occurred throughout the year, but with a peak; 69% ofthe litters were born in December-March (early to mid wet season) when fruits and insects were abundant. Of seven births recorded in one group, interbirth intervals were 6—c.15 months but were usually 8-9 months. Although not showing physical signs, sexual receptivity is reflected in consort behavior (mate guarding) by males, which can extend five days, with copulations occurring on the fourth and fifth day.

Activity patterns. Typical daily activity lasts nearly twelve hours, beginning a little after sunrise at 05:35-06:20 h and ending well before sunset at ¢.17:00-17:55 h; rain can cause an early end to daily activities. Sleeping sites are usually in the crotch or proximal part of a branch, or in a dense vine tangle, in the lower or middle crowns of medium-sized to tall trees overlooking treefalls or low vegetation. After leaving their sleeping sites, Illiger’s Saddle-back Tamarins travel to a nearby fruit source, often where they were eating the previous afternoon, and then dedicate the rest of the morning to foraging for animal prey, with intermittent visits to other fruit sources. A brief resting bout is typical at 08:00 h—10:00 h, but ¢.12:00 h, or in the early afternoon, they spend one to two hours resting and grooming. In the afternoon, they return to foraging, punctuated by visits to fruiting trees or gum sources. They spend c.45% of their time searching for, manipulating, and eating small animal prey, principally insects, 32% grooming and resting, 14% eating fruits, gums, or other plant materials, 6% traveling, and 3% in miscellaneous other activities. As is typical for saddle-back tamarins, Illiger’s Saddle-back Tamarins prefer the lowest levels of the forest, spending 82% of their day below 11 m and only c.2% in the highest stratum above 20 m. About 50% of their day is spent 1-4 m above the ground.

Movements, Home range and Social organization. With a density of 15-18 ind/km? in the Cahuana study area, Illiger’s Saddle-back Tamarins were the third most abundant primate after Black-capped Squirrel Monkeys (Saimiri boliviensis) and Colombian Red Howlers (Alouatta seniculus). Modal group size was six individuals (range 2-10), not including dependent infants. Groups contained a dominant breeding female, her mate, the young from her 1-2 latest litters, and a less stable component of subadults and adults. Home range size of a group studied intensively from 1979 to 1980 was 15-7 ha, increasing in the latter part of the study to 16-5 ha. The group periodically patrolled its home range and often defended its borders, chasing and fighting with members of a neighboring group. The group traveled distances of 1113-1991 m/day (average 1405 m) and was usually in a cohesive unit, with individuals 50 m or less apart. Their ranging patterns changed somewhat between seasons, and they traveled longer distances in the dry season when fruits were scarce. In the wet season when fruits are more abundant, daily movements were shorter, and travel paths were more meandering. The main factors that influenced their daily movements were spatial distribution and availabilities of food resources and the need to patrol their home range boundaries. Capuchin monkeys (Cebus and Sapajus) were also a factor, and Illiger’s Saddle-back Tamarins avoided them when they passed through their home range. When approached by capuchin monkeys, the tamarins became very quiet and evasive, abruptly moving into shrub vegetation, indicating that the capuchins may be occasional predators. Occasionally, solitary or all-male groups of 2-5 Bolivian Squirrel Monkeys followed Illiger’s Saddle-back Tamarins for periods of several days. Relations were not exactly harmonious; when a squirrel monkey moved too close to a resting or feeding tamarin, the tamarin would either confront it with mild threat vocalizations or move away. Squirrel monkeys fed in all fruit trees used by the tamarins and often supplanted them. Likewise, squirrel monkeys foraged for animal prey in the same sites as those used by the tamarins, and Soini regarded them as the most important competitors at his study site. Northern Amazon Red Squirrels (Sciurus igniventris) were usually ignored, although Soini reported once seeing an entire group of Illiger’s Saddle-back Tamarins put to flight from a feeding tree by a squirrel that possibly had a nest there. A number of birds exploit the same insects and fruits as the tamarins. Agressive interactions were seen in fruiting trees between them and Cuvier’s toucans (Ramphastos tucanus cuvien), chestnut-eared aracaris (Pleroglossus castanotis), and speckled chachalacas (Ortalis guttata). Potential predators of the tamarins include birds of prey (accipitrids and falconids) and the Tayra (Eira barbara). They have been seen mobbing snakes; e.g. emerald tree boa (Corallus caninus) high up in a tree and a bushmaster (Lachests muta) resting on the ground between the stilt roots of a tree. In 1980, the density of Mliger’s Saddle-back Tamarins at Cahuana in the Pacaya-Samiria Basin was 15 ind/ km? or 2 groups/km?.

Status and Conservation. CITES Appendix II. Classified as Least Concern on The [UCN Red List (as S. fuscicollis illigeri). Illiger’s Saddle-back Tamarin is endemic to the Peruvian Amazon. It adapts well to areas with human disturbance, often seen visiting plantations of banana and other cultivated fruits. It is rarely hunted in areas where human density is low, and threats to their survival arise only when forests are completely eliminated or fragmented over wide areas for cattle pasture and agriculture. It occurs in the Pacaya-Samiria National Reserve.

Bibliography. Aquino & Encarnacion (1994b), Egozcue et al. (1969), Garber (1993a, 1993b), Hershkovitz (1966, 1977), Garber (1993), Hodun et al. (1981), Matauschek et al. (2011), Snowdon & Soini (1988), Soini (1986, 1987a, 1990a, 1990b), Soini & Coppula (1981), Soini et al. (1989), Tapia et al. (1990).