The effect of intruders on territorial Palestine Sunbirds (Nectarinia osea) during the pre-egg laying period

I. Berger, Y. Leshem, Y. Yom-Tov, S. Markman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


In monogamous species, conspecific aggression is a primary tactic to deter intruders. Alternative reproductive strategies, such as extra-pair copulations or intra-specific brood parasitism that peak at the pre-egg laying period and are practised by intruders, pose a significant threat to the monogamous pair. Here, we addressed the question whether male and female Palestine Sunbirds (Nectarinia osea) demonstrate different aggression levels toward conspecific intruders during the pre-egg laying period. We further asked whether indirect measures of certainty of paternity affect male aggression toward such intruders. For that, we measured the aggression of both partners toward intruders while using stuffed birds. We conducted two experiments on a monogamous and territorial Palestine Sunbird population. In the first experiment, we exposed breeding pairs to a conspecific or a heterospecific intruder and measured their aggression toward it. During the second experiment, we exposed breeding pairs to an intruder, before and after temporarily removing the local male. The local male demonstrated higher aggression than the local female toward a male decoy. Toward a female decoy, the local male demonstrated lower aggression than the local female. Following their release, the removed males did not change their aggression toward the male decoy, but rather they decreased their aggression toward the female decoy. These results suggest that the indirect male's certainty of paternity may be an important factor of the male's interests when he faces a risk of potential intra-specific brood parasitism. Furthermore, these findings suggest that each gender is more sensitive to its similar intruder gender, and acts according to its interests in terms of its aggression toward the intruder.

Original languageEnglish
Pages (from-to)291-299
Number of pages9
JournalJournal fur Ornithologie
Issue number1
StatePublished - Jan 2014


  • Aggression
  • Birds
  • Extra-pair copulations
  • Intra-specific brood parasitism
  • Mate guarding
  • Monogamy


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