|Letter-winged Kite - Pic by Peter McDonald|
I became concerned about the kites during an influx of predominantly inland bird species to coastal areas in 2012-2014. These movements occur from time to time following periods of heavy rainfall inland, when birds breed prolifically. When floodwaters subside and ephemeral wetlands dry up, many birds move to coastal areas. Letter-winged Kites are often among the mix; during one such influx for instance, I found several kites on the beach on North Stradbroke Island (see here) in 1977. In 2012-214, however, there were no reports of Letter-winged Kite from coastal eastern Australia although several other predominantly inland species (such as Black Kite, Black-tailed Native-hen and Australian Painted-Snipe) were turning up in regions such as south-east Queensland, where they are normally absent.
Something appeared to be amiss. Meanwhile, birders travelling the inland were reporting seeing fewer and fewer kites as the years progress in areas where they were once reliable and even quite common at times. The plight of the Letter-winged Kite is highlighted in an article by Sean Dooley in the newly published December 2015 edition of Australian Birdlife; at the time of writing I've not had the opportunity to see the article, but it is encouraging that attention is now being drawn to the matter.
The rainfall events referred to above are usually associated with explosions of populations of the Long-haired Rat (Rattus villosissimus) and other native rodents upon which the kites feed. Letter-winged Kites congregate and nest during these explosions; when rodent numbers subside, kite numbers also decline and the birds disperse.
|Feral cat in a Letter-winged Kite nesting tree - pic by Lindsay Cupper|
Feral cats have been around for many decades but anecdotal evidence suggests that populations are increasing in northern and central Australia. The kites are likely to be impacted in two ways. Adult kites and chicks are known to be killed by cats during nesting events, with entire colonies having been eliminated by feline predation.
As well, cats compete with kites for rodent prey. A study by Chris Pavey and colleagues Stephen Eldridge and Mike Heywood looked at competition between kites and three introduced mammalian predators - dingoes, foxes and cats - over 3.5 years in the early-2000s. They concluded there was considerable potential for food-based competition between the kite and mammalian predators, particularly foxes and cats. While Letter-winged Kites had a very narrow dietary niche (native rodents), mammalian predators could exploit other prey in lean times. The scientists concluded that the mammalian predators captured 11 times as many rodents during the study period as the Letter-winged Kites.
|Feral cats in Letter-winged Kite nest. Pic by Jack Pettigrew|
|Dingo at Night Parrot site. Pic by Steve Murphy|
|Letter-winged Kite. Pic by Lindsay Cupper|
Predation of livestock by dingoes and feral dogs has had serious impacts on the grazing industry, but many farmers in recent years have switched from sheep to cattle, which are much less likely than sheep to be taken by dogs. It may be time for state government authorities to consider the wisdom of continuing their war against dingoes in those parts of the arid zone where Letter-winged Kites and other rare wildlife are threatened by the growing menace of feral cats.