Striated Herons

Striated Herons (Butorides striata), stocky bittern-like herons, are strongly associated with mangroves and tidal estuaries and rivers. 

Please click on photos to enlarge.

Morcombe notes they can be secretive, skulking in shadowy mangroves and emerging at low tide to forage. However they can become relatively tame around manmade structures such as marinas, sea walls and oyster farms for example.

Striated Herons in Victoria are probably best regarded as rare vagrants with just 23 records in Birdata from the Mallacoota – Gypsy Point area between 2008 and 2014 with a peak of sighting records in 2010. There may have been unrecorded sightings since 2014 and eBird may contain additional records.

There are several Striated Herons on the Brunswick River in northern NSW where I found two birds using oyster farm racks to hunt fish on a rising tide. When hunting, the birds adopt a crouched posture. They often crouch low and rigid with intense concentration and focus while waiting for hapless prey to swim into the range of their surprisingly long necks and beaks which they use to make lightning fast lunges to capture fish and other small aquatic prey such as crabs and shrimp. They also stalk prey, once again in a crouched posture – I assume this makes it hard for their prey to see them. When not hunting they adopt a much more relaxed and upright stance. 

When not in hunting mode the Herons are relaxed and assume an upright posture.

In hunting mode they adopt a crouched posture and stalk with intense concentration.

Hunting from on top of the oyster racks required them to have good grip with their strong feet and legs to make vertical downward lunges at the fish below.

All the fish I saw caught were very small – these seemed to be targeted as a preference as there looked to be larger fish present.

A view of the Heron’s back.

A relaxed upright non-hunting posture.

 

The Striated Herons on the Brunswick River certainly make good use of the oyster growing infrastructure. They also forage along constructed rock sea walls and look for fish from mooring lines in the marina.

Oyster farms may be a physical blight on scenic tidal environments however they are an important aquaculture industry and they do provide very useful habitat for roosting/resting and foraging water birds including migrant shorebirds. Also small fish use them as shelters and sources of food.