Common chiffchaff one of the first avian signs that spring has returned. Its call is a "hweet", less disyllabic than the "hooeet" of the willow warbler or "hu-it" of the western Bonelli's warbler. The song differs from that of the Iberian chiffchaff, which has a shorter . However, mixed singers occur in the hybridisation zone and elsewhere, and can be difficult to allocate to species. When not singing, the common chiffchaff can be difficult to distinguish from other leaf warblers with greenish upperparts and whitish underparts, particularly the willow warbler. However, that species has a longer primary projection, a sleeker, brighter appearance
The Genius of Birds The Genius of Birds The Genius of Birds is a 2016 book by nature writer Jennifer Ackerman. "The Genius of Birds" highlights new findings and discoveries in the field of bird intelligence. The book explores birds as thinkers (contrary to the cliché "bird brain") in the context of observed behavior in the wild and brings to it the scientific findings from lab and field research. New research suggests that some birds, such as those in the family corvidae, can rival primates and even humans in forms of intelligence. Much like humans, birds have enormous brains relative to the rest of