10.5061/DRYAD.QJQ2BVQHM
Mangini, G. Giselle
0000-0003-4071-8853
Universidad Nacional de Tucumán-Consejo Nacional de Investigaciones
Científicas y Técnicas
Mokross, Karl
Sao Paulo State University
Gandoy, Facundo
Universidad Nacional de Tucumán-Consejo Nacional de Investigaciones
Científicas y Técnicas
Areta, Juan Ignacio
0000-0001-8588-3030
IBIGEO
Mixed-species flocking is associated with low arthropod detectability and
increased foraging efficiency by Yungas forest birds in Argentina
Dryad
dataset
2021
FOS: Animal and dairy science
2022-01-31T00:00:00Z
2022-01-31T00:00:00Z
en
156140 bytes
3
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Mixed-species flocks presumably provide birds with antipredator and
foraging benefits. The foraging benefits hypothesis predicts that a
reduction in arthropod abundance will trigger flocking activity; however,
flocking activity may also be influenced by the difficulty of detecting
arthropods, a seldom explored possibility. We found that environmental
traits (temperature and foliage density) combined with arthropod abundance
explained arthropod detection by birds in the Yungas foothill forest of NW
Argentina. Prey detection was inversely related to ambient temperature and
foliage density while positively associated with arthropod abundance.
Based on this result, we built a structural equation model using a latent
proxy variable for arthropod detectability, arthropod crypsis, integrating
ambient temperature, foliage density, and proportion of immature
arthropods. This model allowed us to compare the relative importance of
arthropod abundance and the difficulty in detecting prey items as
predictors of flocking propensity. After two years of studying 129
mixed-species flocks, 1,344 bird foraging sequences, and 25,591 arthropod
captures, we found that the flocking propensity of birds was only
significantly correlated with arthropod detectability and not with
arthropod abundance. Flocking propensity peaked when the arthropod
community was comprised of proportionately more immature and non-flying
arthropods, the temperature was low, and the foliage cover was more dense;
all factors are contributing to a low arthropod detectability. Finally, we
evaluated whether joining mixed-species flocks provided foraging benefits
such as increased foraging efficiency. Individuals benefited from joining
flocks by an average increase of their prey-capture attempt rate of 40%,
while the search rate increased by 16%. Our results add a new perspective
on the drivers of mixed-species flocking by showing that the capacity to
find prey items may have a more significant effect than prey abundance per
se.
Data were collected from 20 independent transects 100 m long each. Surveys
were performed on a seasonal basis. Measured variables: 1. Environmental
(temperature and foliage density) 2. Arthropod surveys (two techniques,
beating and passive pitfalls) 3. Birds foraging behavior (behavioral
observations) Three tables are presented: Table 1. For SEM model and
arthropod seasonality Table 2. For Model selection in relation to
environmental and arthropod abundance variables Table 3. Birds behavior
regarding their social condition