Perch Height Research Articles

Shift in the Structural Habitat of Anolis Opalinus Due to Congeneric Competition

The Jamaican Anolis opalinus has different perch height characteristics depending on locality. Toward the center of the island, around Mandeville, A. opalinus characteristically perches low, being classified as a trunk—ground species. In Kingston, however, A. opalinus perches high, classified as a trunk—crown species, Evidence indicates the Kingston A. opalinus would also perch low except that interaction with Anolis I. Lineatophus forces A. opalinus into perch sites higher than appear to be the species' preference.

Studies of the guild of ant-following birds at Belém, Brazil

Abstract Studies of ant-following birds at Belém show that some species are professional ant-followers, that is, obtain more than 50% of their food near ants. Professional ant-followers at Belém are: Black-spotted Bare-Eye, Phlegopsis nigromaculata, White-backed Fire-Eye, Pyriglena leuconota, Scale-backed Antbird, Hylophylax poecilenota (Formicariidae); Barred Woodcreeper, Dendrocolaptes certhia, Plain-brown Woodcreeper, Dendrocincla fuliginosa, White-chinned Woodcreeper, D. merula; and Gray-headed Tanager Eucometis penicillata, A list of thirty-seven species of nonprofessional birds was obtained during the study period. Nonprofessional species only occasionally follow army ant raids. The army ant (Eciton burchelli) was the main species followed. Foraging habits, perch heights and prey items were noted for most of the professional and nonprofessional species of birds. Also, their interactions at swarms of ants and a comparison with other ant-following guilds is provided.

Structural Habitat and Time Budget of a Tropical Anolis Lizard

Structural habitat data generally support the interpretation that competition for food results in habitat partitioning. In this investigation, the importance of ethological factors in determining the structural habitat of Anolis lizards is demonstrated by examining the structural habitat of Anolis polylepis during foraging and social interaction, its two major activities. “Overall” structural habitats show that intraspecific classes use perches of significantly different heights and diameters. Perch heights of adult males and females are also shown to be related to the type of activity in which they are engaged. Overall structural habitat data show a greater difference between the sexes than actually exists in their feeding locations. Ecological differences between insular and continental Anolis potentially affecting the structural habitat are also discussed.

The Ethoecology of Anolis nebulosus (Sauria, Iguanidae)

A population of Anolis nebulosus located near Tepic, Nayarit, Mexico was studied in the field and laboratory from June, 1965 to September, 1968. The population showed a female : male sex ratio of 50:49. The males in the spring were larger than the females, averaging 41.4 and 35.8 mm, respectively; however, no difference in the length-weight relationship occurred between the sexes. The Nayarit study area supported 90 lizards totalling 120 gm/1,000 m2 during the spring, prior to breeding. Few lizards appeared to live more than a year in nature. A. nebulosus were limited baskers, seeking shade when their cloacal temperatures reached approximately 29.7 C. There was a partial subdivision of the habitat between the larger males and the remaining members of the population with regard to perch height and microhabitat. Males also had much larger home ranges than females, averaging 1.99 + 0.23 and 0.62 + 0.14 m2, respectively. There was a trend for the bigger animals to possess larger home ranges. The home ranges were not uniformly distributed on the study area, but were associated with certain features of the habitat. While the home ranges of the large males overlapped those of the smaller males, the large male home ranges were exclusive of those of other large males. Few home ranges of females touched one another, yet the distribution of female home ranges was an almost perfect overlap with the male home ranges. Males and females shared a common behavioral repertoire, although the frequency of use and social context differed at times. Males and females were territorial and showed pronounced agonistic behavior toward members of their own sex. The reproductive season was correlated with the rainy season. Mating lasted from late May through August, and the appearance of hatchlings from the latter part of August to the end of October. 1.Present address: Museum of Comparative Zoology, Haard University, Cambridge, Mass. 02138. 1. Present address: Museum of Comparative Zoology, Harvard University, Cambridge, Mass. 02138. 1970 JOURNAL OF HERPETOLOGY 4(1-2): 1-38 (1) This content downloaded from 157.55.39.215 on Tue, 30 Aug 2016 05:27:40 UTC All use subject to http://about.jstor.org/terms

The Anolis Lizards of Bimini: Resource Partitioning in a Complex Fauna

The tiny island of South Bimini contains 4 species of lizards of he genus Anolis, a number surpassed only on the 4 largest islands of the Greater Antilles and on 2 very large and nearby satellite islands. These species are syntopic with respect to a two—dimensional area of the ground but divide the habitat according to perch height and perch diameter: sagrei is partly terrestrial but occurs more often on small and large low perches; distichus prefers the trunks and large branches of medium to large trees; angusticipes inhabits small twigs, especially at great heights; and carolinensis is found mostly on leaves or on the adjacent twigs and brances. The size classes of the species are staggered in such a way that the interspecific classes which overlap most in habitat overlap least in prey size. Similarities in prey size and prey taxa for classes of the same species are somewhat greater than those expected on the basis of habitat and morphology alone. The distribution of the species among the vegetation communities of Bimini can be explained on the basis of perch height and diameter preference. Within the same species, the larger lizards usually eat larger food, fewer items, and in sagrei more fruit; and they have a greater average range of food size per digestive tract. One species (distichus) is extremely myrmecophagous: about 75—90% of its food items are ants. In 3 of the 4 species, subadult males take more food and average smaller prey then females of the same head length. That species (distichus) which takes the smallest food items and whose classes overlap the most in habitat preference with those of other species is least dimorphic is size between the sexes. It is suggested that such small, nondimorphic species are best suited for insinuation into complex faunas, whereas larger, dimorphic forms are best for the colonization of empty areas. The usefulness of various measures of overlap and specialization is evaluated for this lizard association.

Ecological Distribution in Anoline Lizards of Puerto Rico

The eight species of lizards of the genus Anolis in Puerto Rico can be divided into four morphological similarities. One, Anolis curvieri, is very different from the rest and has not been discussed here. The other seven species fall into three groups. Each of these groups occupies a different structural habitat which can be defined in terms of perch height and perch diameter. Within each of these three groups the species have very similar but not indential structural habitats but differ very widely in climatic habitat defined in terms of shade. Shade preferences seem to result from the temperature preferences of the species involved. In each group there is one species with high shade preference which is essentially restricted to the mountains. Each group also has a species with a lower shade preference which occurs in the lowlands and extends up into the mountains in exposed or sunny situations. One of the three groups has an additional species which is restricted to the hot and southwest corner of Puerto Rico. When one compares the temperature preferences or eccritic temperatures of the various species, one finds in each group that the highland species has a lower eccritic temperature than does the lowland species. There is little temperature difference between the lowland species and arid southwest species in the group where this additional third species is present. The species within each structural habitat show many morphological similarities which may be the result of their being closely related or may be the result of adaptation to similar environments. The differences in microhabitat between the Puerto Rican anoles separate them spatially though not completely. In species occupying different structural habitats in the same area the overlap may involve part of the home range of most of the individuals in the area. In species occupying the same structural but different climatic habitats the overlap may involve all of the home range of some individuals but of only a small fraction of the individuals in the total population. The spatial separation among Puerto Rican Anolis can be suggested to be of ecological significance because it reduces interspecific competition and because it allows the various species to adapt more precisely to different parts of the available habitat. Thus members of a genus may exploit the habitat more efficiently.