It is the time of year when nature gets busy. There are babies everywhere; chickens, ducklings, firetail finches, blue fairy wrens, goanna, black snakes…the list goes on. Most residents of the humpy are finding a mate (or sticking with the one from last year) and settling down to raise a family. Not the Satin bowerbird though; he fancies himself a player. Satin bowerbirds are regarded as pests in our area, they are one of the main reasons all our garden areas are locked up like Fort Knox (along with possums, they are the most garden destructive species I know). They eat any fruit and vegetable plants they can get to and love red fruits (tomato, strawberry, capsicum and yes, even chilli). I find them annoying and fascinating at the same time.
The mature male is a shiny blue/black colour, they are really very beautiful. The female and any males under about five years of age are a greenish yellow, mottled colour with the most extraordinary violet eyes I have ever seen. The breeding behaviour of the Satin bowerbird is what makes them so very interesting. The male Satin bowerbird builds a bower; basically a well decorated clump of grass. He finds as many blue, silver or otherwise shiny objects as he can to decorate with, endlessly fussing with the placement of ornaments. Bowerbirds will steal pieces from other male’s bowers. When I was a child there was a certain blue plastic hammer (about 30cm long) which used to migrate from bower to bower every year. It was something of a game to find the bower with the hammer. I still marvel at the determination of those males; carrying a toy larger than themselves over distances of up to a kilometer. I wonder if that blue hammer is still being passed around. All of this effort is designed to attract as many females as possible. These birds have even been known to paint their bower with crushed berries and mud (mulberries beware). The female comes down to see his bower (several times in fact) and if she aproves of the bower she will stay to watch his mating dance (he flutters around and makes whirring noises then dashes back and forward, some even roll over. Then… if he is lucky…she will mate with him. After which she leaves to start her career as a single mother and the male continues to try to attract more females. This has evolved as a very efficient way to spread genes as females do not choose the same male to mate with every year. At some point between the house viewing and the stage show the female will go off and build herself a messy stick nest (the bird version of a humpy) so as to have somewhere to lay eggs after mating. These nests are not easy to find and I do not see baby bowerbird very often until they get to the leaving home (or fledging) stage. Judging by the number of surviving young I believe that female Satin bowerbirds are very good mothers who rarely lose their young. The natural diet of the bowerbird is native fruits such as figs, wild raspberries, lilly pilly and other berries. Of course that means they eat what we grow in our gardens (being fruit based as well). Their role in the environment is to spread seed so that new plants can grow. To that end their digestive system is somewhat messy; they eat a lot of fruit but digest only parts of it, they then poop the seed and some partially digested waste out in a sort of spray pattern, usually from a fairly high branch. This means that plants such as wild raspberry can have its seed distributed to new locations. This charming habit also makes raising a baby bowerbird (or any other frugivore) a messy, smelly job. They do tend to be friendly, intelligent and endearing as well though. The females often forage for dog biscuits and other protein rich foods while feeding young. I have seen some taking meat scraps from the chook pen now and then also. While they are undoubtedly a source of destruction and annoyance in the garden, the Satin bowerbird is a valuable part of the ecology and is important to our biodiversity. If you find a bowerbird eating your dog biscuits in the spring, spare a thought for the single mother lifestyle she leads and let her have a few.