Vol. 58, 2019
(update: 2019.05.31; 07.12)
Nest Concealment and Nest
Defence by Two Passerines: Effect of Protective Nesting Association
Marcin
Polak
doi:10.6620/ZS.2019.58-15
Department
of Nature Conservation, Institute of Biology and Biochemistry, Maria
Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland. Tel:
+ 48-081-537-59-71. E-mail: mpolak@hektor.umcs.lublin.pl
Received 11 February 2019 / Accepted 29 May 2019
Communicated by Chih-Ming Hung
Selection
of favourable micro-habitat conditions at nest-sites and nest defence
can be important antipredatory strategies in open-cup nesting birds. In
response to nest predation risks, some species of birds appear to form
protective nesting associations in which both may gain benefits due to
mutual warning and nest defence. Despite the many studies assessing the
impact of various factors on nest defence and nest placement, how
interactions between species while breeding can modify these strategies
is still poorly understood. Here I evaluate whether nesting
associations in two species influence nest defence intensity and
nest-site selection. An observational approach was used to analyse the
defensive behaviours of the Barred Warbler Sylvia nisoria and Red-backed Shrike Lanius collurio
in an agricultural landscape in eastern Poland. Association was
determined by the position of the nest with respect to that of the
associated species (by the nest of one species being within the
breeding territory of the other). Nest defence behaviour of these two
passerines was assessed as their response to a human intruder near an
active brood. This study showed that the nest size and visibility were
similar in nest-sites of pairs nesting in association and in spatial
isolation. Barred Warblers nesting within shrike breeding territories
strongly defended their nests. Warblers breeding alone displayed a
lower level of defence than birds nested in association. Shrikes not
nesting with warblers were significantly more aggressive than those
breeding in
the protective nesting association. I suggest that shrikes tried to
compensate for the lack of assistance by warblers in joint nest defence
and were forced to invest more into defending their own nests. This
research suggests that positive interactions within the heterospecific
network of relations in ecosystems may be one of the factors
responsible for diversifying the intensity of avian nest defence.
Key words: Positive interaction, Antipredator
response, Nest defence, Protective nesting association, Lanius collurio, Sylvia nisoria.
Citation:
Polak M. 2019. Nest concealment and nest defence by two passerines:
effect of protective nesting association. Zool Stud 58:15. doi:10.6620/ZS.2019.58-15.
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