Sarah Belfield - Reporter and writer, freelance

s a r a h b e l f i e l d

reporter & writer, freelance

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MAGPIES TURN THEIR CHEEK ON JUNK FOOD

(Australasian Science, September 2006)

Are we doing the Australian magpie irreparable damage by feeding it tidbits in our backyards? Sarah Belfield finds that while processed foods can quickly alter the bird's natural equilibrium, the news is not all bad.

SOMETHING magpies have in common with humans is that a long-term diet of junk food could be dangerous to their health.

In a recently published study, University of Queensland researchers Greg Baxter and Goh Ishigame found that mince for pets, tasty cheese and dog-food sausage all quickly and significantly raised the level of cholesterol in magpies' blood plasma.

This happened for free-ranging and captive magpies fed on the processed foods. Their cholesterol levels rose against reference levels found in magpies kept at Sydney's Taronga Zoo.

In the captive feeding program, six magpies ate as much of a given food as they wanted over 2 days, before being switched to the next food. Over the total 6-day span, their average cholesterol level increased from 2.48 mMol/L at capture to 3.4 mMol/L at the end of the study. The highest figure in the range for the Taronga magpies had been 2.94 mMol/L.

"We found the same results here with our [captive] magpies as you might see if you locked people up, told them not to get any exercise and fed them junk food," Baxter said. "So, following on from that, you would probably expect the same sorts of effects — coronary heart disease, arthritis, diabetes, all those sorts of things." The stress of captivity may have influenced the results, but Baxter said his gut feeling was that the food was responsible for the cholesterol change.

On average, each magpie helped itself to 42 grams of food per day. It meant the birds were "probably stuffed to the gills", according to Baxter. While the total weight of food eaten may not have been as high as what a wild bird would polish off during a day spent flying around, the density of nutrients would be much higher, he said.

For the 70 free-ranging magpies studied, this time over 20 weeks, daily servings of 20-40 grams of dog sausage saw cholesterol levels leap to an average 3.23 mMol/L.

Baxter said the work demonstrated that "even with what we regard as 'just backyard feeding' — a relatively casual, unplanned activity people do — you can definitely affect body chemistry in subject birds." In contrast, a natural diet of berries, grasshoppers and earthworms doesn't ramp up cholesterol in a magpie.

But while the captive couch-potatoes happily wolfed down their free lunches, another recently-published study has shown most magpies in the wild seem to know the meaning of moderation. Griffith University researcher Darryl Jones said his group looked at what adult magpies ate when there was plenty of natural food available. What they found surprised them.

Both "fed" and "unfed" magpies — birds that did and didn't use feeding stations — chose to eat a predominantly natural diet. On average, 76% of all items eaten by fed birds were naturally foraged morsels, compared with 92% for the unfed birds. While the difference itself was significant, the overall result was "really reassuring", according to Jones, who said he was initially "as skeptical as everybody else". He had thought the fed birds would pig out on the junk food.

"Goh and Greg's work has shown that, long term, too fatty a food is going to be bad [for magpies]. But the reassuring thing is, given a choice, they don't concentrate on it � at least [not] normal, breeding adults," he said. Rather, they used feeding-station food as a supplement to their normal, natural diet.

Jones said the only evidence he had of birds "pretty much living off" the meat trays people leave out was for some of the juveniles. "They haven't got a territory of their own, they haven't gone away and found a mate, for example. And so they're just hanging around like a bunch of teenagers. They're the ones that don't go off feeding [naturally]. But eventually they will."

The worry that magpies become dependent on food hand-outs was "probably the biggest issue that people ask me to talk about", according to Jones, who gives many public lectures on wildlife feeding. "I say, 'Look, we actually have to face the fact. For most of the animals that come to visit us, this is a cup of tea and a Tim Tam.' It's just a little snack."

This is the case even for people who spend substantial amounts of money each year on feeding magpies and other birds. "This is the passionate thing in their life," Jones said. "But they have [felt] unable to go on holidays, or go away for any length of time because they're so worried about the animals.

"The problem is how do you tell them, 'Actually, these animals that you desperately think [you] are keeping alive, they'll just go up to the next people, or just don't care.' It would be hard for these people to appreciate this."

Jones was also surprised that, on the whole, the fed and unfed magpies he studied eschewed the fast-food option for feeding their hungry broods. "I would have argued just from common sense that by the time there's three starving, hungry, demanding chicks in the nest, why would they spend so much extra time and effort digging up worms when they could just ferry food from a feed tray and not have to do anything?

"They seem to know that to feed chicks you've got to do the natural diet." So on an individual basis, magpies and their chicks seemed to be faring well, even though the food humans put out "aren't really appropriate".

But what was a worry, both Baxter and Jones said, was the documented effect feeding had on urban magpie populations. The onset time of breeding, number of breeding cycles per season, clutch sizes, hatching rates, and chick survival rates were concerns.

"[Feeding] is the reason, without a doubt, that the density of magpies in the suburban environment is about five times what it is anywhere else. There's just so many more magpies," Jones said.

"On a small scale at your backyard level, the little bit of feeding you're doing is probably not doing too much damage to the birds you're interested in. However, because you and your neighbour and twenty people up the street all do the same thing, and the whole city does the same thing, that is having a profound effect on the community of species that live in cities."

Jones said the most unbiased survey done on magpie feeding put 38% of households in the 'feeder' category, defined as money being spent on food given out. Households putting out food scraps weren't included in the figure.

Chris Lloyd, executive officer of the New South Wales Wildlife Information and Rescue Service (WIRES), which in the summer sends out about 50 or 60 bird-feeding leaflets per week in response to specific requests, said Australians considered it "some kind of birthright" to have a magpie sing in the backyard.

Other problems associated with feeding were the spread of diseases among birds, and beak rot after meat gets stuck inside their mouths. But Lloyd says you don't need to feed them to receive visits. "If you create the habitat, they'll come and carol away at you anyway."

Assuming a household wasn't stubbornly wedded to backyard feeding, WIRES usually helped people to find out how to make their backyard a haven for a range of birds. "We generally will get a field guide out, or a coloured coffee-table book ... and just walk them through and say 'You haven't got that bird, but you can get it if you do this, that and the other'."

Lloyd said putting out a water bath was a problem solver. "Keep it in the sun with a little bit of tree cover over that and you'll have birds doing much more interesting things in it," he said. He found people got excited about the prospect of birds doing something more entertaining than to "just stand up on their verandah and holler for food in the old way". Birds often frolicked and bathed for half-hour intervals.

He said WIRES was increasingly visiting the suburbs and towns that retirees flock to, where a lot of the bird feeding went on. A spin-off of talks given by current wildlife carers was new recruits. "[We are] using the exercise as saying 'All this bird feeding is doing the following... How would you like to really play with animals?' Because that's really what it comes down to.

"There's a vast difference between sticking out some rather mangy mince for a magpie and actually having four chicks in a cage that you're rearing for release, who are gape-feeding off you... If we could turn half of these backyards into organised places where the birds could be looked after, nobody would ever bother putting a feeding station out and they'd know why not."

s a r a h b e l f i e l d reporter & writer, freelance

About Services Clips Ideas Contact	Sample clip MAGPIES TURN THEIR CHEEK ON JUNK FOOD (Australasian Science, September 2006) Are we doing the Australian magpie irreparable damage by feeding it tidbits in our backyards? Sarah Belfield finds that while processed foods can quickly alter the bird's natural equilibrium, the news is not all bad. SOMETHING magpies have in common with humans is that a long-term diet of junk food could be dangerous to their health. In a recently published study, University of Queensland researchers Greg Baxter and Goh Ishigame found that mince for pets, tasty cheese and dog-food sausage all quickly and significantly raised the level of cholesterol in magpies' blood plasma. This happened for free-ranging and captive magpies fed on the processed foods. Their cholesterol levels rose against reference levels found in magpies kept at Sydney's Taronga Zoo. In the captive feeding program, six magpies ate as much of a given food as they wanted over 2 days, before being switched to the next food. Over the total 6-day span, their average cholesterol level increased from 2.48 mMol/L at capture to 3.4 mMol/L at the end of the study. The highest figure in the range for the Taronga magpies had been 2.94 mMol/L. "We found the same results here with our [captive] magpies as you might see if you locked people up, told them not to get any exercise and fed them junk food," Baxter said. "So, following on from that, you would probably expect the same sorts of effects — coronary heart disease, arthritis, diabetes, all those sorts of things." The stress of captivity may have influenced the results, but Baxter said his gut feeling was that the food was responsible for the cholesterol change. On average, each magpie helped itself to 42 grams of food per day. It meant the birds were "probably stuffed to the gills", according to Baxter. While the total weight of food eaten may not have been as high as what a wild bird would polish off during a day spent flying around, the density of nutrients would be much higher, he said. For the 70 free-ranging magpies studied, this time over 20 weeks, daily servings of 20-40 grams of dog sausage saw cholesterol levels leap to an average 3.23 mMol/L. Baxter said the work demonstrated that "even with what we regard as 'just backyard feeding' — a relatively casual, unplanned activity people do — you can definitely affect body chemistry in subject birds." In contrast, a natural diet of berries, grasshoppers and earthworms doesn't ramp up cholesterol in a magpie. But while the captive couch-potatoes happily wolfed down their free lunches, another recently-published study has shown most magpies in the wild seem to know the meaning of moderation. Griffith University researcher Darryl Jones said his group looked at what adult magpies ate when there was plenty of natural food available. What they found surprised them. Both "fed" and "unfed" magpies — birds that did and didn't use feeding stations — chose to eat a predominantly natural diet. On average, 76% of all items eaten by fed birds were naturally foraged morsels, compared with 92% for the unfed birds. While the difference itself was significant, the overall result was "really reassuring", according to Jones, who said he was initially "as skeptical as everybody else". He had thought the fed birds would pig out on the junk food. "Goh and Greg's work has shown that, long term, too fatty a food is going to be bad [for magpies]. But the reassuring thing is, given a choice, they don't concentrate on it � at least [not] normal, breeding adults," he said. Rather, they used feeding-station food as a supplement to their normal, natural diet. Jones said the only evidence he had of birds "pretty much living off" the meat trays people leave out was for some of the juveniles. "They haven't got a territory of their own, they haven't gone away and found a mate, for example. And so they're just hanging around like a bunch of teenagers. They're the ones that don't go off feeding [naturally]. But eventually they will." The worry that magpies become dependent on food hand-outs was "probably the biggest issue that people ask me to talk about", according to Jones, who gives many public lectures on wildlife feeding. "I say, 'Look, we actually have to face the fact. For most of the animals that come to visit us, this is a cup of tea and a Tim Tam.' It's just a little snack." This is the case even for people who spend substantial amounts of money each year on feeding magpies and other birds. "This is the passionate thing in their life," Jones said. "But they have [felt] unable to go on holidays, or go away for any length of time because they're so worried about the animals. "The problem is how do you tell them, 'Actually, these animals that you desperately think [you] are keeping alive, they'll just go up to the next people, or just don't care.' It would be hard for these people to appreciate this." Jones was also surprised that, on the whole, the fed and unfed magpies he studied eschewed the fast-food option for feeding their hungry broods. "I would have argued just from common sense that by the time there's three starving, hungry, demanding chicks in the nest, why would they spend so much extra time and effort digging up worms when they could just ferry food from a feed tray and not have to do anything? "They seem to know that to feed chicks you've got to do the natural diet." So on an individual basis, magpies and their chicks seemed to be faring well, even though the food humans put out "aren't really appropriate". But what was a worry, both Baxter and Jones said, was the documented effect feeding had on urban magpie populations. The onset time of breeding, number of breeding cycles per season, clutch sizes, hatching rates, and chick survival rates were concerns. "[Feeding] is the reason, without a doubt, that the density of magpies in the suburban environment is about five times what it is anywhere else. There's just so many more magpies," Jones said. "On a small scale at your backyard level, the little bit of feeding you're doing is probably not doing too much damage to the birds you're interested in. However, because you and your neighbour and twenty people up the street all do the same thing, and the whole city does the same thing, that is having a profound effect on the community of species that live in cities." Jones said the most unbiased survey done on magpie feeding put 38% of households in the 'feeder' category, defined as money being spent on food given out. Households putting out food scraps weren't included in the figure. Chris Lloyd, executive officer of the New South Wales Wildlife Information and Rescue Service (WIRES), which in the summer sends out about 50 or 60 bird-feeding leaflets per week in response to specific requests, said Australians considered it "some kind of birthright" to have a magpie sing in the backyard. Other problems associated with feeding were the spread of diseases among birds, and beak rot after meat gets stuck inside their mouths. But Lloyd says you don't need to feed them to receive visits. "If you create the habitat, they'll come and carol away at you anyway." Assuming a household wasn't stubbornly wedded to backyard feeding, WIRES usually helped people to find out how to make their backyard a haven for a range of birds. "We generally will get a field guide out, or a coloured coffee-table book ... and just walk them through and say 'You haven't got that bird, but you can get it if you do this, that and the other'." Lloyd said putting out a water bath was a problem solver. "Keep it in the sun with a little bit of tree cover over that and you'll have birds doing much more interesting things in it," he said. He found people got excited about the prospect of birds doing something more entertaining than to "just stand up on their verandah and holler for food in the old way". Birds often frolicked and bathed for half-hour intervals. He said WIRES was increasingly visiting the suburbs and towns that retirees flock to, where a lot of the bird feeding went on. A spin-off of talks given by current wildlife carers was new recruits. "[We are] using the exercise as saying 'All this bird feeding is doing the following... How would you like to really play with animals?' Because that's really what it comes down to. "There's a vast difference between sticking out some rather mangy mince for a magpie and actually having four chicks in a cage that you're rearing for release, who are gape-feeding off you... If we could turn half of these backyards into organised places where the birds could be looked after, nobody would ever bother putting a feeding station out and they'd know why not."
	Copyright © 2006-2007 Sarah Belfield. All rights reserved.