Monday, 26 October 2020

Blind Snake killed by Tawny Frogmouth

I found this dead Blackish Blind Snake Anilios nigriscens yesterday below a Tawny Frogmouth nest. It was lying directly below the birds' nest where there were two well-grown chicks, days form fledging. The snake was in amongst the scattering of droppings from the chicks, and there were two distinct pinches in the body, indicating where a frogmouth had gripped the snake when thrashing it against a branch to kill it prior to delivering it to the chicks. There were broken scales on the head indicating this, see image below. 

The nest was on the branch of a Yellow Box Eucalyptus melliodora. The adult male bird on the nest can be seen here against the sky. Less easily seen is the female two branches below.

Blind snakes are only nearly-blind. They hunt by following invertebrates such as ants and termites in burrows and have evolved scales over their tiny eyes, seen here as faint black spots 3-4 scales back from the snout. They seldom venture above ground except after rain, and 27 mm of rain fell in Canberra in the 48 hours previous to this find. Its burrow had probably been flooded. On one of these wet evenings, I watched another frogmouth hunting small invertebrates on the edge of a road. It sat on a sign post or branch and watched for prey to move. There were obviously plenty, as the bird only sat on a perch for a less than a minute at a time before pouncing down and carrying off some small animal to its young back at their nest. This snake, at 44 mm long, would have been an easy find and capture. 

Blind Snakes are almost defenseless against such attacks. They have very small mouths and cannot bite like an elapid snake. They can twist and turn, and release foul-smelling odour, but neither of these strategies would protect it against a frogmouth. I do wonder though, why was it lying below the nest. This is the largest snake recorded to have been killed by a Tawny  Frogmouth, twice the size of the previous record. Was it too large for a chick to swallow. Or had it been dropped between adult and chick by accident. I believe the latter scenario, as such a large snake must have been difficult for the birds to maneuver between mouths, especially inexperienced young mouths. 


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