A sighting of five species of hawk over the Smythesdale landfill prompted the questions, “What are they all eating? Do they have the same prey? Are they in competition with each other?”
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The hawks involved are swamp harrier, little eagle, whistling kite, black kite and brown falcon.
The first four of these are large birds, while the fifth is smaller. Many of them take the same or similar prey.
The two kites are mainly scavengers, feeding mostly on dead rather than living birds and animals. Sometimes they will hunt living creatures, such as rats, rabbits and lizards, as well as birds of various sizes, particularly injured or young ones. Both will also take large insects such as crickets and grasshoppers.
The black kite also feeds on garbage, hence its frequent presence around the Smythesdale landfill site.
Around wetlands, the whistling kite often takes dead fish and slow or injured waterbirds.
Swamp harriers are very much hunters of waterbirds too, as well as frogs, lizards, rabbits and large insects. They take mostly living prey and will live up to their name by “harrying” (hunting and harassing) swimming and diving waterbirds such as ducklings, coots and grebes.
The little eagle is another raptor hunting living prey. This is usually rabbits, with occasional birds and reptiles. The prey in today’s photo is a dusky moorhen, an uncommon item for a little eagle. This is a Lake Wendouree photo.
Being the smallest of the five, the brown falcon takes smaller creatures. It is usually not a bird-hunter, preferring mice, young rabbits, crickets, lizards and grasshoppers. However, it sometimes takes small birds such as sparrows and larks.
Each one of these five raptors takes rabbits as prey, so in that regard they are very useful and under-rated pest controllers. Some take the living animal, while others prefer dead ones (roadkills), and others prefer smaller ones.
Much of their other prey is similar too, but there are probably sufficient differences in their tastes, their hunting methods and their preferred habitats to ensure that they do not seriously compete with each other for food.
Each of the five species sometimes circles high in the air, but all their prey is collected down at ground level.
TENCH AT LAKE WENDOUREE
A sighting of a 25-centimetre golden-brown fish with black fins on the bank of Lake Wendouree indicates that tench, a European fish in the same family as the carp, are once again present. I was not aware that this species had returned to the lake.
