(ISI Web of Science 10-05-2011)
AU CARRASCAL, LM
TI BASKING AND ANTIPREDATOR BEHAVIOR IN A HIGH-ALTITUDE LIZARD - IMPLICATIONS OF HEAT-EXCHANGE RATE
SO ETHOLOGY (1992) 92:143-154
AB This paper presents an observational and experimental study of the basking behaviour and heat exchange rate of the montane lizard Lacerta monticola. The results obtained by these procedures were coupled in order to understand behavioural mechanims promoting effective thermoregulation at high altitudes. Heating rate was higher when body size was smaller, and substrate temperature and sun rays incidence angle were higher. The lizards cooled faster when body size and substrate temperature were lower, and when the body temperature of the lizard going into shadow was higher. Time exposed to sun and mean duration of basking periods were longer early in the morning, while bask frequency increased through the morning. Our results suggest that time devoted to basking is mainly obtained by regulating bask duration. Lizards obtained the necessary time for heating by means of long basking periods. Mean travel distance per minute and distance to the nearest refuge increased from early morning to midday. These behavioural variables were tightly correlated with the expected heating rate of individuals. Body size affects thermoregulatory behaviour as well as locomotor activity. Juvenile lizards, with small body mass and high surface-to-volume ratios, were subjected to faster heating and cooling rates, basked more frequently than adults (but during shorter periods), and devoted more time to locomotion than adults. The thermoregulatory behaviour of L. monticola is the result of the combination of shuttling heliothermy by basking and the exploitation of thermal opportunities offered by patches in shade through thermal exchange with the substrate.
TC 68 citas
AU MORENO, E
TI LEG MORPHOLOGY AND FEEDING POSTURES IN 4 PARUS-SPECIES - AN EXPERIMENTAL ECOMORPHOLOGICAL APPROACH
SO ECOLOGY (1993) 74:2037-2044
AB The foraging behavior of four Parus species feeding at artificial feeders was studied, while controlling for ecological variables related to patch characteristics (food quality, food access, and escape distance to the nearest refuge). Hindlimb morphology (osteology and myology) was analyzed and compared with foraging postures at feeders. Using the Long-Tailed Tit as an appropriate outgroup for comparison, and considering functional changes associated with morphological changes, we demonstrated the existence of clear ecomorphological patterns relating foraging postures and hindlimb morphology in the four Parus species studied. The Blue Tit uses hanging postures preferably and its hindlimb morphology is modified for helping leg flexion. The Crested Tit more often stands and its hindlimb morphology is modified to aid leg extension. Great and Coal Tits are ecologically and morphologically intermediate between the two former species. Our results show morphology as a determinant of locomotion mode. Since foraging postures are tightly associated with substrate use, then morphology should be considered when studying pressures determining community organization. Our proposed integrative method for dealing with ecomorphology can be valuable in demonstrating the adaptiveness of morphological structures in phylogenetically and ecologically related species.
TC 41 citas
AU DIAZ, JA
TI REGIONAL DISTRIBUTION OF A MEDITERRANEAN LIZARD - INFLUENCE OF HABITAT CUES AND PREY ABUNDANCE
SO JOURNAL OF BIOGEOGRAPHY (1991) 18:291-297
AB We studied the distribution of a common Mediterranean lacertid lizard, Psammodromus algirus (L.) 1758, on nineteen sites within a regional gradient of homogeneous yet contrasted habitats. This scale was large enough to allow line-transect estimates of lizard abundance, which were related to quantitative (and when possible multivariate) measurements of the structure and floristic composition of vegetation, the abundance of arthropod prey, the relative density of other lizard species, and the climatic data obtained from nearby meteorological stations. Neither the climate not the abundance of other lizards seemed to condition the quantitative distribution of the species. The positive influence of broad-leaved forests on the abundance of P. algirus appeared to be a consequence of structure attributes more directly related to the ecology of lizards than floristic composition per se. Thus, population levels were most highly correlated with the cover of shrubs over 20 cm in height, and once this structural requirement was met, they increased with the abundance of potential prey (itself conditioned by vegetation cover at the ground level and litter cover). We suggest that our results should be interpreted in the context of thermoregulatory, predator avoidance and movement minimization strategies whose influence on survival, and hence abundance, could probably be applied to other insectivorous lizards from temperate zones.
TC 42 citas
AU CARRASCAL, LM
TI ECOMORPHOLOGICAL RELATIONSHIPS IN A GROUP OF INSECTIVOROUS BIRDS OF TEMPERATE FORESTS IN WINTER
SO HOLARCTIC ECOLOGY (1990) 13:105-111
AB We examined the relationships between morphology and foraging behaviour in a group of insectivorous birds wintering in temperate mixed forests in northern Iberia. Using principal components analysis we reduced 11 biometric variables to three major morphological components and 20 foraging categories to four major ecological factors. The relative length of the tarsometatarsus and bill morphology were the most important morphological variables predicting foraging ecology. Birds exploiting distal parts of trees and foliage were generally smaller and had relatively longer tarsometatarsi than those foraging on trunks. Foraging on the ground and branches of medium diameter was associated with bill thickness. Ecomorphological patterns were discernable at the level of substrate use and foraging methods, but bear no relation to selection of tree species or foraging height. Morphology correctly predicted niche breadth and interspecific overlap. In Parus spp. interspecific differences in bill shape could explain 63% of the interspecific segregation according to substrate use.
TC 32 citas
AU CARRASCAL, LM
TI BIRD SIZE AND DENSITY - A REGIONAL APPROACH
SO AMERICAN NATURALIST (1991) 138:777-784.
AB This paper investigateS the relationship between weight (W)
and density (d) in small insectivorous birds of the Basque Country
(North of Spain). Ecological densities (di) were estimated using
line transects in the 10 most extensive habitats of the region (47 species
weighing between 6 g -Regulus ignicapillus- and
TC 20 citas