27 May 2011

Tawny Frogmouth - Podargus strigoides

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Tawny Frogmouth - Podargus strigoides

Frogmouth birds are more closely related to the Nightjars despite superficially looking like an Owl, but have no close relationship with them although they do have a common ancestor dating back 60 or more million years. There are many differences between these groups, but most obviously is the small sharply pointed beak and taloned feet of owls that are used to catch and eat largely small vertebrate prey. Frogmouths on the other hand only have large mouths to grab usually smaller prey that are swallowed whole. Prey for these birds besides including small vertebrates, also involves a high portion of invertebrates.

Owls are not commonly seen around Esperance as there are relatively few large trees with nesting hollows in which they can breed, whereas the more common Tawny Frogmouth builds a simple stick nest in the fork of a branch, thereby making the local sparse tree heathland more suitable for them. The above photographs were enabled by one of these birds bumping into the house floor to ceiling grass doors, probably to catch a moth. It was not a hard collision so the bird was not harmed, but decided to check things out from ground level, which allowed me to quickly take a few photos through the glass before it flew off.

The size of Tawny Frogmouths are apparently highly variable with the southern Podargus strigoides subsp. strigoides being much larger than its northern cousin and can exceed ½ metre (20”) in length. Interestingly, most references state this species of Frogmouth has yellow eyes, but you will notice the one above has bright orange/red ones and more like the Papuan Frogmouth eye color. However after some research on the internet I came across a comprehensive program run by the Western Sydney Institute of TAFE, Richmond called the ‘Husbandry Guidelines for Tawny Frogmouth’ by Phipps, Salkeld and Walker in which they state “The eye of a Tawny Frogmouth is yellow as is the inside of the mouth and throat. However across some of the sub-species the eye colour can vary from a pale yellow to a deep orange.”

Regarding the identification of gender, apparently with Frogmouths this is not easy to do as both sexes are very similar although the male is often slightly larger, but you need to have them together to appreciate the difference. And again from the same reference above “Furthermore these dimorphic characteristics cannot be relied upon in all cases to determine the sex of individuals. Therefore I would consider Tawny Frogmouths to be monomorphic.”