Have you wondered why some birds adorn their nests with eye-catching objects such as colorful ribbons and yarn, butterfly and beetle wings, shells, silver spoons, flower petals, food wrappers, garden tools, keys, screws, jewelry, and other trinkets? Whereas some items are *thought *to provide structural support, camouflage, insulation, predator protection, or insect repellant, many other articles seem purely ornamental. Is there a deeper significance to these decorative efforts than simple nest beautification?
A study reported in the Jan. 21 issue of *Science* describing the use of white plastic1 nest decorations by Black Kites (*Milvus migrans*) explores this behavior as possible intraspecies communication. [*“Raptor Nest Decorations Are a Reliable Threat Against Conspecifics.”* F. Sergio, et al. *Science, *Vol. 331 No. 6015, January 21, 2011.* *A pdf of this article is available at: <http://bama.ua.edu/~rlearley/Sergio_2011.pdf>.] Sergio’s team looked at nest decorations as signals of individual fitness and territorial dominance in Black Kites, a raptor common across Europe, Asia, Africa, and Australia. Fitter birds with the best territories put larger amounts of shredded white plastic in their nests than weaker birds and are rarely intimidated, while kites using less white plastic are repeatedly challenged for territory. Offspring in highly ornamented nests are also less threatened and are rarely attacked by other Black Kites. Whereas bowerbirds and Black Wheateaters are famous for ornamenting their nests to attract mates, hundreds of other birds, from penguins to passerines, also embellish their nests with extraneous, and sometimes bizarre, objects. The question is why? Like the kites, are these objects used to say something meaningful about the nest builder? The authors question if birds are weaving hidden messages in their nests and suggest that intraspecies communication via nest decorations (and other extended phenotypic signals2) may be far more common than previously thought—in birds, fish, and mammals [especially humans]. Keep one eye on the sky and one on the nest. Candace Cornell 1 The authors believe that Black Kites used white feathers in their nest before the availability of white plastic. 2 A simplified definition of an extended phenotypic signal is information conveyed by the manipulative actions or construction behaviors of an individual animal. For a formal definition and discussion, see "*Extended Phenotypes as Signals*." Franziska C. Schaedelin and Michael Taborsky, *Biol. Rev*. (2009), 84, pp. 293–313. A pdf version is available at < http://behav.zoology.unibe.ch/sysuif/uploads/files/esh/pdf_online/ taborskym/Schaedelin_BiolRev2009.pdf>. -- Cayugabirds-L List Info: http://www.NortheastBirding.com/CayugabirdsWELCOME http://www.NortheastBirding.com/CayugabirdsRULES ARCHIVES: 1) http://www.mail-archive.com/[email protected]/maillist.html 2) http://birdingonthe.net/mailinglists/CAYU.html 3) http://www.surfbirds.com/birdingmail/Group/Cayugabirds Please submit your observations to eBird: http://ebird.org/content/ebird/ --
