The rate of sick or injured barn owls reported to Wildlife Victoria so far this year has increased by 875 per cent on the same period last year.

In 2018 Wildlife Victoria received over 117 rescue requests for barn owls between January to mid-July.

The year prior during the same period, there were only 12.

Pictures of dead owls shared online

In the coastal town of Port Fairy, locals have taken to social media to share their experiences.

Chelsea Fox found a dead barn owl on her Port Fairy property with no apparent visible sign of injury.

After she posted a photo to Facebook it sparked a flood of people sharing similar experiences online.

At least nine other friends had found dead barn owls in the surrounding area in the week prior.

Ms Fox found a second dead owl just days later on a friend's property in Killarney.

Two-year-old Asha was devastated to find this sick barn owl on her family's Killarney property. It died shortly after they found it. ( Supplied: Chelsea Fox )

Rat poison to blame?

Both Bird Life Australia and the Department of Environment, Land, Water and Planning (DELWP) have named rat bait as being the most likely cause of death in barn owls.

"During winter, we see a spike in raptor deaths following their consumption of vermin that have ingested household rat poison," Mark Breguet, Program Manager of Compliance Operations in the Barwon South West area, said.

"This is due to an increase in vermin making their way into households during the colder months."

Mr Breguet also said that they have not recently received any reports to warrant an investigation into this matter.

Starving in the winter months

Wildlife Victoria Operations Manager Emily Small said that the large increase in sick and injured owls can also be attributed to starvation.

"There is not enough food to sustain their population," she said.

During summer the owls prey on rat and mice, but during winter populations decrease and the rodents seek the warm dry conditions inside houses and barns.

"Most of the rescue cases we are receiving are lethargic owls on the ground, some close to death," Ms Small said.

"They are emaciated and weak.

"It is hard to discern here if they are suffering from poison or starvation."

A rescued barn owl awaits its new temporary home with a wildlife carer, where it will be fed raw meat and live mice to build up stamina. ( Supplied: Wildlife Victoria )

Editor of Australian Birdlife Magazine Sean Dooley thinks drought might be playing a part.

"Inland drought conditions and related summer rodent plagues could have caused an increase in owl populations over the warmer months," he said.

He proposed that the onset of cold weather may have pushed the owls to unknown, coastal territories looking for new food sources.

"Once they're out of their territory, they're less successful at finding the food," he said.

"At this time of year, you get birds on the move looking for food, basically starving."

Not just barn owls being poisoned

Mr Dooley said that research conducted by a Western Australian study has shown high levels of pesticide in another owl species, the boobook owl.

"A worrying problem that is emerging through research, is that is has shown significant levels of pesticide — particularly the stuff you use to poison rats and mice — in many of our owl and raptor populations," he said.

A study of dead Boobook owls in 2017 found that 70 per cent had consumed rodenticide poison. That research was conducted by PhD student Michael Lohr in Western Australia. ( Supplied: Simon Cherriman )

The research was carried out in 2017 by PhD student Michael Lohr, who performed necropsies on over 70 dead boobook owls, most of which were roadkill.

He found that 70 per cent of the boobook owls he tested had measurable levels of rat poisoning in their blood.

"[The poison] may contribute to road death or being attacked by cats or dogs," Mr Lohr told ABC Perth in 2017.

"Furthermore 18 per cent of the boobook owls tested had lethal levels of second-generation rodenticide — that is, the rat bait that sticks around in the system rather than breaking down."

What alternatives are there?

Wildlife Victoria recommends not to use poison rodent baits and suggests instead humane methods such as live trapping to control a rodent problems.

"It is not only the barn owls who will be affected (by bait), it's also the majestic powerful owl, wedged-tailed eagles and boobook owls," Ms Small said.

Am example of a non-poison based 'tilt' trap, considered to be humane, available for sale in many hardware stores. ( ABC South West Vic: Emily Bissland )

However people living in rural towns can find themselves fighting a losing battle against household rodents.

Ms Fox has also experienced the challenge of rat and mice plagues in the past.

"I think everyone's baiting up," she said.

"It's a really tricky one, people are trying to keep the mice down in their homes yet its just having this devastating effect.

"I don't know what the alternatives are when they're in plague proportions, and I think they have been lately."

There are older, first-generation poisons such as Warfarin developed in the 1940s that can be used to bait rodents and are less harmful for wildlife, but many families with young children or dogs wish to avoid baits altogether.

In that case, tidying up the pantry, removing all food sources, using traps and blocking any gaps in the walls are the most common suggestions.

A hand-reared, orphaned barn owl gently grabs the nose of vet, Dr Katrina Gregory, who raised the owl. ( ABC Open: Dr Keith Stead )

While he said he understands how challenging rural mice plagues can be, Birdlife Australia's Sean Dooley believes that baiting rodents is a short-term fix.

"You're shooting yourself in the foot," he said.

"You're playing a losing game if you're doing mass poisoning, because it's poisoning the predators that can help you control the numbers in the long term."

Mr Dooley said that encouraging natural predators onto your property can help.

"You can encourage barn owls onto your property either by putting nesting boxes up or keeping old dead hollow trees, which they'll also nest in."

Scheduled review unlikely to take rat bait off the shelf

The Australian Pesticides and Veterinary Medicines Authority (APVMA) is the regulator of agricultural and veterinary chemicals in Australia.

They have recently commenced a detailed scoping exercise (meaning a review has not started — but they are looking at starting it) for the reconsideration of 'second generation anti-coagulant rodenticides'.

These are rodent baits that contain poisons which do not break down quickly after the target animal ingests them.

A review would look at scientific data such as Mr Lohr's study together with consultation with the chemical industry and the general public.

However the authority was reluctant to make any suggestion that second generation rodenticides might be banned.

"APVMA cannot pre-empt the outcomes of the future review," a spokesperson said in a statement to the ABC.

"The review will consider if the continued use of these products according to label directions continues to meet contemporary safety standards."

The APVMA website stated that one of the primary reasons that seconded-generation anti-coagulants have been listed as a 'priority 2' chemical for review is that they are killing native wildlife.

People who find sick or injured birds of prey are urged to contact wildlife carers or DELWP on 136 186.