- Irruption: when large numbers of a particular species move to an area where they are not commonly found in large numbers, often in response to drought, rainfall or other environmental changes. In Australia, some species of hawks and kites can irrupt into areas experiencing mouse plagues or locusts. Water birds irrupt into areas experiencing sudden flooding.
An irruption of birds can be a spectacular event. This is something that happens quite regularly in Australia, often as a result of our wildly fluctuating environmental conditions.
I can remember back to about 1990 when there was a serious mouse plague in the wheat growing areas east of home. Millions of mice infested sheds and barns on the local farms. During this time we went on a camping holiday to Hattah-Kulkyne National Park.We drove through this area and it was impossible not to run over hundreds of mice as we drove along. In fact, there were so many dead mice on the road, they caused corrugations. It was a rough ride.
While we were travelling along we kept looking out for Letter-winged Kites. This species is usually confined to areas much further north. Because of the mice plagues they had moved south in significant numbers and were seen in the area we drove through. This Kite is a rather hard species to find normally. I was excited at the prospect of seeing at least one. I still haven’t seen one. [sigh]
On other occasions I have seen large numbers of other species. I remember seeing literally thousands of Black-tailed Native-hens on the road south of home on our way to Meningie. Normally we might see two or three. At other times Australian Pelicans have been known to breed up in huge numbers, especially after flooding in some areas.
Lake Eyre in flood:
As I write this in mid-March (2007) Lake Eyre in far north South Australia is filling with flood waters from heavy rain in parts of Queensland. This lake is usually a dry salt lake. Over coming months, many species of water birds will breed in massive numbers in response to this water. In a year or two, as the lake dries out, there may well be an irruption of some of these species as they move in large numbers to other parts of the country.
- Gregarious: some birds live in groups and are said to be gregarious. One such species is the White-Winged Chough. They are usually seen in groups of from 5 to 10, though the family group that visits my garden has been up to 12 in size. I have seen larger groups than that in other places.
There is some truth in the saying “birds of a feather flock together.” In Australia it is quite common to see large flocks of birds of the one species. There are few sights as beautiful as a flock of several hundred pink Galahs wheeling through the deep blue Australian sky. Corellas and cockatoos also flock together, feeding together on the ground in large groups numbering in the hundreds, or even thousands.
Another amazing sight is to see a large flock of budgerigars feeding together. As they fly off – sometimes in their thousands – it is like a swiftly moving green cloud before your eyes. When such a flock lands in a dead tree, it suddenly seems to spring back to life once again.
Some of our finches are also quite gregarious. These flocks may only number in the dozens but in their own small way can be just as spectacular. They bring great delight to the observer when such groups visit a watering point (such as a bird bath) or a feeding tray in a park or someone’s garden.
Waterbirds can also be said to be gregarious, their numbers can often be in the thousands. Rafts of ducks, mudflats seething with waders and nesting cormorants in their thousands can be an inspiring sight and an attack on the ears (and nose in the case of cormorants).
- Hybridisation: the cross-breeding between different species.
Most species stay true to their kind. King Parrots breed with King Parrots and produce young King Parrots. Occasionally, one species will interbreed with another species. In some parts of Australia the introduced species of duck, the Mallards, will hybridise with the native Pacific Black Duck. The offspring show characteristics of both species. These offspring may also breed, though success rates tend to be poor (citation).
For more about hybrid species of animals and plants click here.
UPDATE: One of my regular readers and frequent commenters has added some interesting observations of bird hybridisations in the comments section. I have copied and pasted this below. I inviteyou to add your observations in the comments section.
When we used to live in northern NSW, we had a malaysian lady in town who like to try to FORCE hybridization of various Australian Parrots. One day, we thought we had a new bird for our garden list, but the closest we could put it to was a Superb Parrot, though it wasnÃ¢â‚¬â„¢t Ã¢â‚¬ËœrightÃ¢â‚¬â„¢ and we were out of range. Eventually, we heard that one of ConnieÃ¢â‚¬â„¢s Ã¢â‚¬Å“creationsÃ¢â‚¬Â had escaped – a hybrid between a Mallee Ringneck and a Pale-headed Rosella! It didnÃ¢â‚¬â„¢t stay long, but whether through misadventure or Ã¢â‚¬ËœtravelÃ¢â‚¬â„¢ IÃ¢â‚¬â„¢m not sure. The neighbours also had a Galah in a cage, to which lots of local Galahs got attracted, including one which had paired with a Little Corella. For about 20 years, they brought their offspring (like pale, washed out Galahs, with a yellow Ã¢â‚¬ËœwashÃ¢â‚¬â„¢) to feed on spilled seed each year, but none ever lasted more than a season. One day, we saw a dead Corella by the highway, and this Ã¢â‚¬ËœpairÃ¢â‚¬â„¢ never returned, so it must have been that one.
Thanks to John for these observations.
- Flight feathers: these are the well developed feathers on the wings and tail which are used in flight. The wing feathers consist of primaries, secondaries and tertiaries.
I have tried a number of times to capture the flight of various birds, generally with not much luck. In many cases the flight feathers show up brilliant colours or patterns not apparent when the bird is viewed sitting. I remember one attempt late last year when a number of Whiskered Terns were skimming low over us on the edge of Lake Alexandrina while we had a cuppa. For nearly an hour I tried to get a photo; only blurred images or cloud shots resulted. Very frustrating. With more time and experience – not to mention cooperative birds – I will succeed in capturing some great shots one day. In the meantime, you have to be satisfied with this photo of a Caspian Tern.
Updated November 2013.
Ever wonder where bird names come from? And what they mean?
Harry over at his blog called Heraclitean Fire had fun with the dictionary recently. He discovered some interesting things about words and birds. He tells about his discoveries in a post called Birding the Dictionary.
- Glossary of bird words – learn more about birds and their words here.