Oology Oology Oology (or oölogy) is a branch of ornithology studying bird eggs, nests and breeding behaviour. The word is derived from the Greek "oion", meaning egg. Oology can also refer to the hobby of collecting wild birds' eggs, sometimes called egg collecting, birdnesting or egging, which is now illegal in many jurisdictions. Oology became increasingly popular in Britain and the United States during the 1800s. Observing birds from afar was difficult because high quality binoculars were not readily available. Thus it was often more practical to shoot the birds, or collect their eggs. While the collection of the eggs of
What Love Is Made Of extremely positive about "What Love Is Made Of", describing it as "darker than anything" from "On a Mission", while calling it "slinky". The reviewer went on to commend the "irresistibly pouty" chorus. Pitchfork Media's Katherine St. Asaph commented that, in the song, the singer "sound[ed] completely enthralled, by either her lover or the music" and complimented her voice, noting that it seemed "ten times bigger than before". Jordan Sargent of "Spin" magazine called the track "exuberant" and highlighted Katy's vocal performance, which he deemed "typically fantastic", while the team from pop music website Popjustice gave "What Love Is Made Of"