Habitat use of Tropical Screech Owl (Megascops choliba) and Burrowing Owl (Athene
cunicularia) on patches of cerrado in state of São Paulo, Brazil
Ana Claudia Rocha Braga
Abstract
The Cerrado biome is the largest, richest and perhaps
the most threatened tropical savannah of the world.
However, most part of its natural areas has been
transformed on agrosystems and pastures where basic
principles of conservation weren’t respected. Each
biological group or taxa are affected on different ways
by this change. Birds of prey are particularly affected
because of its position in trophic webs, as they are top
predators. To understand how these birds are affected
by change caused by human land use, it is necessary to
understand which factors are important for habitat
selection, and then understand the species-habitat
relationship. Thus, we observed ecological aspects of
two widespread and common owls on Brazil: Tropical
Screech-Owls (Megascops choliba) and Burrowing
Owl (Athene cunicularia). The main objectives of this
study included an analysis of methodological aspects
of studying these owls species through playback and
observe their habitat use. The study was conducted in
the Estação Ecológica de Itirapina, State of São Paulo,
Brazil. For doing it, we used playback experiments to
detect these owls on four different cerrado
physiognomies Vocal activities of Tropical Screechowls were more detected in conditions of higher
temperature and humidity. On the other hand, the
Athene cunicularia answered more to playback in
lower wind speed conditions and/or at full moon
nights. The Burrowing Owl explored more frequently
open physiognomies of cerrado, as campo limpo and
campo sujo (Hk-w = 9.976; p = 0.0188). Conversely,
Megascops choliba is more often found on campo
cerrado, avoiding campo limpo (Hk-w = 10.88; p =
0.0137). According to Aikaike’s Information Criterion
(AIC) selection model, the most important variable to
explain the distribution of both species in cerrado is
the number of trees. There was ecological segregation
between Megascops choliba and A.cunicularia. The
spatial niche was intermediarily segregated (Pianka´s
niche overlap measure O = 0.466), according their
different needs for nesting and foraging. Additionally,
these owls displayed broader (M. choliba Bst = 0.753)
or intermediate (A. cunicularia Bst = 0.453) spatial
niche breadths. On this sense, these owls have
different needs on habitat selection, and their different
distributions in cerrado were related more intrinsically
to the number of trees present on each physiognomy,
which is related to their nesting and foraging
requirements. Aditionally, this study suggests, the
importance to consider the influence of weather
http://www.biotaneotropica.org.br
conditions on broadcast survey techniques for
nocturnal raptors, which may be considered in further
studies on census of these birds.
Key-words: Athene cunicularia, cerrado, habitat use,
playback, Megascops choliba
Braga, Ana Claudia Rocha
Uso do hábitat da corujinha-do-mato
Megascops choliba e da coruja-buraqueira Athene
cunicularia (Strigiformes: Strigidae) em
remanescentes de cerrado da região central do Estado
de São Paulo.
Número de páginas
Dissertação (Mestrado) - Instituto de
Biociências da Universidade de São Paulo.
Departamento de Ecologia.
1. Uso do habitat 2. Megascops choliba 3.
Athene cunicularia I. Universidade de São Paulo.
Instituto de Biociências. Departamento de Ecologia.