Large Monitor Lizards Guard Sheep in Australia
Hasslefly vermin not just a nuisance, but a potential threat. These wormy critters can burrow into wounds, which is troublesome for sheep in Australia particularly. Scientists are therefore probing remedies for these animals and have stumbled upon an indigenous creature that has been around for centuries.
Specific fly vermin larvae thrive on deep injuries on sheep, often leading to the animals' demise due to their wounds. As per reports in the journal "Ecology and Evolution," native monitor lizards mitigate the risk of this by feasting on dead flesh. Monitor lizards, consequently, munch on decaying carcasses on which fewer fly vermin can breed, which in turn would subsequently lay their eggs on sheep.
Sheep farmers could save a considerable amount by protecting monitor lizards for their flocks, according to the study. "Fly vermin present a major predicament for the Australian sheep business. They induce a terrible ailment, controlling which is expensive for farmers and a significant concern for the sheep's welfare," stated first author Tom Jameson from the University of Cambridge.
Monitor lizards superior to foreign species
The native Rosenberg monitors supposedly lessen the number of such parasites more proficiently than imported species like foxes and cats, according to the researchers' study. The extent to which this impacts the infestation of sheep is yet to be determined. Rosenberg monitors (Varanus rosenbergi) are indigenous to the arid landscapes of South Australia and can mature up to one and a half meters long.
European settlers brought foxes and cats to Australia in the 18th century. The native flora and fauna population has suffered since, according to the team. "The results suggest that in the battle against invasive species in South Australia, attention should also be paid to bolstering the population of Rosenberg monitors and other native species, as they are crucial for the entire ecosystem," stated Jameson.
The researchers set up stations with camera traps and dead rats as bait on the south Australian Yorke Peninsula. After five days, they checked each time how much of the rat had been consumed and how many wormy critters were on the carcass. From the camera footage, it could be inferred which carrion feeder had discovered the dead rat - and how swiftly. A Rosenberg monitor was found to have discovered the dead rat relatively frequently and quicker than a fox or cat on average.
Birds also vital carrion feeders
Altogether, eight species of carrion feeders were observed at the stations, including ravens, magpies, and tree kangaroos. Birds were the most regular carrion feeders. The researchers then closely logged how much of the carrion was consumed and how many wormy critter eggs the remaining portion still housed. "It was gross - we counted the wormy critters," stated Jameson. An unconsumed rat was found to be infested with an average of over 1000 wormy critters after five days.
"These wormy critters spawn flies that can spread up to 20 kilometers within a week and pose a risk of a fly infestation to sheep herds in the vicinity." The removal of dead animals from pastures, therefore, plays a significant role in the control of myiasis.
This pertains to blow fly species such as Lucilia cuprina, Calliphora nociva, and Calliphora albifrontalis. They lay their eggs on carrion, but also in wounds of vertebrates. The wriggly critters often feed on decaying tissue, but can also feed on healthy tissue. Depending on the location on the animal's body and the strength of the infestation, this can lead to a painful death for the affected animal.
Sheep are highly alluring to blow flies due to their frequently filthy wool, which is commonly soiled with sweat, droppings, and urine. The parasitic infestation known as myiasis reduces the value of the sheep or leads to its demise. The annual damage to Australian sheep farmers, according to the Australian Agriculture Ministry, is estimated to be around 280 million Australian dollars.
