Use of exotic conifers as nesting sites by Black-faced Ibis (Theristicus melanopis melanopis) in an urban area of southern Chile

Abstract

We studied the influence of seven habitat variables, including tree species, for nesting by the Black-faced Ibis (Theristicus melanopis melanopis) in an urban area of southern Chile. Variables were compared between 30 trees with nests and 30 randomly selected trees without nests. Nests were found in big trees with large diameters and heights. However, the only variable found to have a significant effect on site selection was tree species, which explained 57.9% of data variability (deviance) and suggested a selection of exotic conifers, mainly Douglas fir (Pseudotsuga menziesii). Tree species and tree diameter also had significant effects upon the number of nests per tree, jointly explaining 68.9% of data deviance. Our results suggest that in urban environments the Black-faced Ibis uses larger trees that provide greater nest stability and protection.

Investigamos la influencia de siete factores sobre el uso del hábitat de nidificación de la bandurria Theristicus melanopis melanopis en un área urbana del sur de Chile. Comparamos las mediciones de estas variables entre 30 árboles-nido y 30 árboles seleccionados al azar. Los nidos de T. melanopis fueron encontrados en árboles de gran DAP y altura. Sin embargo, encontramos que la especie de árbol fue la única variable explicativa que tuvo un efecto significativo sobre el uso de hábitat, utilizando coníferas exóticas, principalmente Pseudotsuga menziesii. La variable especie de árbol explicó el 57.9% de la variabilidad (desviación) de los datos. Encontramos además que esta variable, junto con el diámetro del árbol, tuvo efectos significativos sobre el número de nidos por árbol, explicando en conjunto el 68.9% de la devianza de los datos. Nuestros resultados sugieren que, en ambientes urbanos, T. melanopis usa grandes árboles que proveen estabilidad y protección a los nidos.

Keywords:

• exotic trees
• Osorno
• Threskiornithidae
• tree use
• urban ecology
• urban nesting

Acknowledgments

The authors are grateful to all those who permitted access to their homes or business premises, in particular to V. Sáez (administrator of the Olimpia Sports Club). P. Valladares helped identifying urban flora. R. Matus and J.E. Jiménez provided literature highly relevant to this study. The help of C.B. Anderson with the final version of the manuscript is greatly appreciated. Two anonymous reviewers substantially improved this work. J.R. Rau acknowledges the Department of Geography at the University of Coimbra, Portugal, where a previous version of this work was prepared. The help of Drs. Anne Zillikens and Angela Schmitz-Ornés is gratefully acknowledged.

Additional information

Funding

The first author, V. Raimilla, was supported by the “Premio Nacional de Ciencias Nibaldo Bahamonde Fellowship”, granted by the Universidad de Los Lagos. The Universidad de Los Lagos Research Direction supported S. Angus, who translated the original version of this manuscript.