Mobbing incident at Toa Payoh!

N. Sivasothi — Mon, 10 Mar 2008 14:10:00 GMT

"Mobbing of Spotted Wood Owl at Toa Payoh," contributed by Gloria Seow. Bird Ecology Study Group, 27 Jan 2008.

“Throwing back the little ones”

N. Sivasothi — Wed, 05 Mar 2008 09:01:24 GMT

Fisheries biologist David O. Conover is investigating the claim that perhaps the "big fish" simply don't exist anymore. According to his work, many fish are evolving smaller body sizes. He is studying the impact of fishing practises on our lakes, streams, and oceans. 'Humans may be causing major evolutionary changes in the fish species that are most important to us economically.' See how the body size of silversides evolved in the lab - “Throwing back the little ones,” The University of California Museum of Paleontology, Berkeley, USA.

Gender role reversal in the Wattled Jacana

N. Sivasothi — Wed, 05 Mar 2008 01:11:55 GMT

Emlen, S. T. & P. H. Wrege, 2004. Size dimorphism, intrasexual competition and sexual selection in Wattled Jacana (Jacana jacana) a sex-role reversed shorebird in Panama. The Auk, Apr 2004.
Photo source: Wikipedia

Abstract - We studied sexual size dimorphism, intrasexual competition, and sexual selection in an individually marked population of Wattled Jacanas (Jacana jacana) in the Republic of Panama.
Males are the sole incubators of eggs (28-day incubation) and primary providers of chick care (50-60 days). Females were 48% heavier than, and behaviorally dominant over, males. Females also showed greater development of secondary sexual characters (fleshy facial ornamentation and wing spurs) than males.
Both sexes defended territories throughout the year against same-sex conspecifics. Competition for territorial space was intense, and many individuals of both sexes did not become breeders. Resident females further competed with one another to accumulate multiple mates, resulting in a mating system of simultaneous polyandry.
Female and male residents (territory holders) were larger, heavier, and more ornamented than adult floaters of the same sex. Larger and heavier females also had more mates than smaller females. Body size was thus a critical predictor of success in intrasexual competition for territories (both sexes) and for mates (females). ...click to read more.

LSM1303 ANIMAL BEHAVIOUR : adaptation

Mobbing incident at Toa Payoh!

“Throwing back the little ones”

Gender role reversal in the Wattled Jacana