(ISI Web of Science 22-01-2007)
AU Carrascal, LM
Polo, V
TI Coal tits, Parus
ater, lose weight in response to chases by predators
SO ANIMAL BEHAVIOUR (1999)
58:281-285.
AB Theoretical models
predict that birds should decrease their body mass in response to increased
predation risk because lighter birds take off faster and are more manoeuvrable.
We studied the effect of predation risk by chasing coal tits in large outdoor
aviaries thus simulating an attempt to capture them. With this increase in
predation risk, both perceived and actual, coal tits lost significantly more
weight than in a control situation when they were not pursued. This pattern was
attributable to a smaller gain in weight only during the day; nocturnal weight
did not change in relation to diurnal predation risk. The lower daily weight
gain was not consistent with predictions from models of interrupted foraging,
but war consistent with predictions from risk adjustment models. Moreover,
there was no difference in weight gain over 2-h periods that included a 1-h
fast and those in which feeding was ad libitum, suggesting that coal tits could
easily regain their body mass after a predator had interrupted their feeding.
Our results therefore suggest that pursuit by predators leads to a decrease in
the body mass of small birds. (C) 1999 The Association for the Study of Animal
Behaviour.
TC 16 citas
AU Polo, V
Carrascal, LM
TI Shaping the body mass
distribution of Passeriformes: habitat use and body mass are evolutionarily and
ecologically related
SO JOURNAL OF ANIMAL
ECOLOGY (1999) 68:324-337.
AB 1. The effect of
habitat structure on the distribution of the number of species by body size
classes was analysed for 277 Passeriformes of the Western Palearctic.
2. The evolutionary history of the group accounted for 68 % of the interspecific
variation in body mass (estimated with the phylogenetic autoregressive method).
The phylogenetic effect decreased from the most recent taxonomic level towards
the earlier phases of evolutionary history. In a more fine-grained study with a
subset of 55 passerine species living in central Spain, phylogeny explained
significant proportions of the interspecific variation in body mass (62%),
habitat use (foraging on the ground vs. foraging in the foliage of scrub/trees;
27%) and structural complexity of preferred habitats (12% ).
3. Throughout the evolutionary history there has been a considerable
concentration of species around a body mass of 10-40 g (increase in kurtosis).
and species with greater body masses have also appeal-ed (increase in
skewness).
4. When the effect of evolutionary history on present-day variation in body
mass was removed (specific component of the phylogenetic autoregressive
method), the distributions of body masses changed with the structural
complexity of preferred, habitats: species from woodland habitats were lighter
(mainly because of the large frequency of small-sized species) and their body
masses were less concentrated around the modal class than in species from
open-country habitats. Results for the phylogenetic component (attributable to
the phylogenetic relatedness of the species) were similar to those of the
specific component.
5. Habitat use (i.e. the use of foraging substrata) was strongly correlated
with body mass in a subset of 55 species living in central Spain: species
foraging on the ground were heavier than those foraging in foliage and small
branches of scrub/trees. This result was significant with both specific and
phylogenetic components. Habitat use and structural complexity of preferred
habitats were significantly correlated using both the specific and the
phylogenetic components: species that mainly forage on the ground are mainly
open-country species, while species that forage in pliable and slender
substrata have mainly woodland habitats. Structural complexity of preferred
habitats was negatively related to body mass, although this correlation was
only significant using phylogenetic residuals (specific component).
6. These results show that the evolutionary history of Western Palearctic
Passeriformes has not produced neutral variation in body mass with respect to
habitat preferences and habitat use.
TC 14 citas
AU Carrascal, LM
Senar, JC
Mozetich, I
Uribe, F
Domenech, J
TI Interactions among
environmental stress, body condition, nutritional status, and dominance in
great tits
SO AUK (1998) 115:727-738.
AB We studied body
condition and feather growth rate in Great Tits (Parus major) in relation to
dominance in two localities during late autumn and early winter. The two
localities differed in elevation, ambient temperature, and arthropod
availability. We supplemented the two study areas with food (husked peanuts)
throughout the study period. The percentage of time tits spent at feeders was
higher at El Ventorrillo (the locality that was colder and had lower natural food
availability) and was associated with dominance only at this locality. The
number of aggressive displacements per hour experienced by each individual was
150 times higher in the area with lower arthropod availability and lower
temperatures. Protein reserves (measured as pectoralis muscle thickness) were
higher at El Ventorrillo and were positively and consistently related to
dominance at both localities. Growth rate of induced feathers was slower at Fl
Ventorrillo but was not directly related to dominance in either locality. Only
dominant adult males at El Ventorrillo compensated for the environmental
harshness at this locality by attaining a higher feather growth rate than the
other sex/age classes. Feather-mass asymmetry of induced feathers during autumn
was not associated with body condition, did not change between localities, and
was inversely and consistently related to dominance at both localities. The
covariation among variables describing bird size, access to supplemental food,
body condition, feather growth rate, and asymmetry was different at the two
localities. Larger, dominant Great Tits spent more time foraging at feeders,
had a thicker pectoralis muscle (i.e. body condition), and grew induced
feathers at a higher rate only at the locality with colder temperatures and
lower food availability.
TC 24 citas
AU Belliure, J
Carrascal, LM
Díaz, JA
TI Covariation of
thermal biology and foraging mode in two Mediterranean lacertid lizards
SO ECOLOGY (1996)
77:1163-1173.
AB Body temperatures, heat
exchange rates, behavioral thermoregulation, and movement behavior (as an index
of foraging mode) were studied in two widely distributed, medium-sized lacertid
lizards (Acanthodactylus erythrurus and Psammodromus algirus). P. algirus
mainly inhabits broad-leaved forests, whereas A. erythrurus prefers open, sandy
areas with sparsely distributed vegetation. These habitat preferences parallel
differences between the areas in which both genera presumably originated:
Eurosaharian xeric steppes with high operative temperatures (T-e) for
Acanthodactylus, and Mediterranean open forests with lower T-e for
Psammodromus.
Field observations showed that percentage of time spent basking and basking
rate (number of basks per minute) were negatively related to T-e, although
average bask duration was not. Percentage of time spent moving, moving rate
(number of moves per minute), and the average duration of individual moves were
inversely related to T-e and were higher in P. algirus. The percentage of total
locomotion time that was spent moving in the shade was also higher in P.
algirus. Behavioral thermoregulation strategies differed in a laboratory
thermogradient, where P. algirus basked more often and for shorter periods and
selected warmer patches than did A. erythrurus. Selected body temperatures
(T-b) in a laboratory thermogradient were significantly higher in A. erythrurus
than in P. algirus. Shade Seeking T-b was higher in A. erythrurus, but Resume
Basking T-b did not differ significantly between the two species. Heating and cooling
rates also differed in the two species: A. erythrurus warmed more slowly and
cooled faster than did P. algirus.
Our data support the existence of a complex syndrome that combines aspects of
the behavior, physiology, and ecology of both species. The thermal consequences
of inhabiting a certain type of habitat can be counterbalanced by behavioral
and physiological means that, in turn, affect movement and, hence, foraging
behavior. Thus, the more active species (P. algirus) heated faster, cooled more
slowly, and basked more often but for shorter periods and at warmer patches
than the less active species (A. erythrurus).
TC 25 citas
AU CARRASCAL, LM
MORENO, E
VALIDO, A
TI MORPHOLOGICAL
EVOLUTION AND CHANGES IN FORAGING BEHAVIOR OF ISLAND AND MAINLAND POPULATIONS
OF BLUE TIT (PARUS-CAERULEUS) - A TEST OF CONVERGENCE AND ECOMORPHOLOGICAL
HYPOTHESES
SO EVOLUTIONARY ECOLOGY
(1994) 8:25-35.
AB We study the leg
morphology and feeding postures of two subspecies of the Blue Tit (Parus
caeruleus; Tenerife island and the Iberian Peninsula) and the Coal Tit (Parus
ater; Iberian Peninsula). We search for evidence supporting the hypothesis of
convergent evolution in morphological and ecological traits and we discuss the
role of ecomorphological hypotheses as predictors of foraging differences at
the intraspecific level. To overcome the problems introduced by environmental
characteristics not related to locomotion and competition, we make observations
under controlled situations to manage food quality and food access. We determine
that the island Blue Tit has a longer tarsometatarsus, larger foot span and a
more proximal insertion of the tibialis cranialis muscle (flexor of the
tarsometatarsus) than the mainland Blue Tit. These morphological differences
are consistent with the more frequent use of hanging and clinging 'head-up'
postures by the Iberian Blue Tit. Several ecomorphological hypotheses obtained
at the interspecific level with other taxa, have proved to be of high
predictive value for explaining ecological differences considering
morphological evolution. The Tenerife Blue Tit and the Iberian Coal Tit clearly
show close convergence in both feeding postures and leg structure, although
some differences in morphology were found between these two species.
Convergence in foraging methods between the island Blue Tit and the mainland
Coal Tit can be explained without considering current interspecific competition
as a determinant of niche space.
TC 14 citas