13 - magpie anatomy and diet

It is a crisp, sunny winter's morning, and we have opened the doors to the garden. IA took this occasion to wander into the living room and looked if we had dropped anything edible on the tiled floor. This is a first, wandering into our house to graze. This time of year lawn beetles have gone through their lifecycle, and the magpies have spent less time foraging in our garden of late, so maybe this is why IA ventured indoors. As magpies are omnivores and as there is no shortage of food they can forage on, this behaviour could also be attributed to curiosity or opportunism. Today I am writing about some findings regarding magpie anatomy, how they find food underground, and about their diet.

IA listening-in on her food / foraging in our garden

Magpies have a hard and relatively thick, 'all-purpose' beak, with a pointed tip. Their beak works equally well for feeding on plant matter, as for crushing beetles that have a hard shell, breaking open hard soil, or fighting. Magpies can injure or even kill an intruder with their beak.

The much shorter beak of nestlings grows to adult size, by the time they are three months old.
I learned this fact from an excellent book that I just bought: 'The Australian Magpie - Biology and Behaviour of an Unusual Songbird', by Gisela Kaplan (see http://www.une.edu.au/__data/assets/pdf_file/0004/65551/MagpieBookCSIRO.pdf and/or http://www.publish.csiro.au/pid/3880.htm). Professor Kaplan is a researcher and teaches at the Centre for Neuroscience and Animal Behaviour at the University of New England, Armidale, NSW (Australia). She has studied magpies for well over ten years and has spent thousands of hours observing these birds. I can highly recommend her book, and am quoting from Professor Kaplan's findings about magpie anatomy and diet in the following paragraphs.

Even though the ability to fly imposes anatomical restrictions, it also means that flight has enabled birds to colonise nearly all habitats on earth, including islands. From  the magpie book I learned that the anatomical adaptation to a habitat is called adaptive radiation, and that restrictions have paradoxically produced a very high degree of variation: there are nearly 9000 species of birds, with a great variety of colouration, locomotion, feeding etc.

I have mentioned beaks, but did you know that birds do not have sweat glands, although water loss through the skin has been observed in some bird species. Magpies therefore control heat by rapid respiration where there is a very high load of heat. Magpies can also cool off and get rid of some heat through changes in skin blood flow, and they do this by positioning their feathers in a certain way and by lifting their wings. As an aside, because magpie nests are high up in trees and usually exposed to the elements, the female adult shields her brood by standing over them with her wings outspread, to provide shade from the sun or protection from heavy rain.

Magpies close their eyelids from the bottom lid upwards, usually only when they sleep or when they are in great pain. From Professor Kaplan's book I also learned that, in order to moisturise their eyes, birds have a third eyelid, called the nicitating membrane, that traverses the eye from the lower inner part outwards and up.

With regards to the head, magpies (like most corvids) have a very large upper hyperstriatum, also called 'wulst', in their large brain. This wulst is the area where visual information is processed and could mean that the magpie's long-distance vision is excellent and its acuity superior to that of an average human. I have observed my magpie family emitting alarm calls when they spotted eagles that were high up in the sky. The birds' hearing is also excellent, and they use it to great effect for locating food such as scarab larvae underground. This brings us to the magpie diet.

Foods consumed by Australian magpies
Magpies forage on the ground, and only feed above ground during breeding time when they feed their nestlings. Else trees are for roosting and breeding as far as magpies are concerned. When IA and IB were fledglings, I saw them walk with their parents on garden lawns and learning to forage. Magpies have a very varied diet, and substantial skills in acquiring their food items.
I already mentioned that they listen to the very slight sounds that larvae and earthworms make underground. Professor Kaplan refers to a study by Floyd and Woodland in 1981, that furnished conclusive proof that magpies find scarab larvae by sound (and sometimes vibrations) alone, and not by visual or olfactory clues. She writes that the researchers had recorded the minute sounds of movements made by scarab larvae and then, using minute speakers buried underground, playing back the recorded sounds. The magpies detected the sounds, located and digged up the speakers!

This 'listening' for food has to be learned and therefore fledgling magpies walk close to the adults, learning to link this sound to food.

Apart from earthworms, beetles and larvae, magpie also eat invertebrates such as snails, millipedes, mantids, crickets, grasshoppers, weevils, bees, at least eight varieties of ant, moths, crustaceans, spiders, scorpions, and all manner of insects.

They also eat reptilians and amphibians such as skinks, and frogs, and mammals such as mice and other small rodents.

To round up magpie diet, being omnivores they also like plant matter, such as seeds, grains, tubers, walnuts, figs and prickly pears.

12 - a duet and a territorial dispute

Today was exciting. First, IA and IB were duetting, see attached video. Duetting is a form of communication where one bird initiates a call, IA in this instance, and another one, his sibling IB, answers. This form of song is useful if the birds cannot see each other and want to establish visual contact. In this case IB sat in a tree nearby, just out of view of IA, who was perched on a chair in the garden. The siblings duet regularly, and it may also function as a way to reinforce bonding between the two birds.

Duetting is a sequential song. If birds sing at the same time then this is referred to as carolling.

Carolling is usually harsher and is used to reaffirm territorial ownership. This happened today as well, but later in the afternoon, when I suddenly heard a lot of calling and saw wings flapping in the garden. On closer inspection I found that two large magpies had intruded on the family's territory, and were dive-bombed by the adults in the garden.

By the time I grabbed a camera and started shooting a video, the magpie family sat on the power line and it started to rain shortly thereafter. The siblings stayed close together throughout, with IA flying off from the power line last, already drenched. One of the adults held the fort just a little longer, sitting on the fence, and looking at the intruders who carried on foraging in our neighbour's garden quite unperturbed, before flying off to join the rest of the family.

11 - brief update

Our neighbour's dog has been escaping and camped in our garden, so the local wildlife has kept a respectful distance. However, a faulty gate has now been fixed, and the magpies are slowly returning. I should have some time over the weekend to observe the magpie family, and will soon report more.

10 - wiping the beak

Having observed IA just now, I am quite convinced that one of the reasons why magpies wipe their beak is to clean it. Have a look at the video clip. At the beginning you can see that IA has been eating something really messy and is wiping its beak on the back of the old outdoors seat. IA then forages on the lawn and wipes its beak again in the grass.

09 - flying up a brick wall

I noticed IB flying up the brick wall, but when I went outside to explore, I could not see any prey animal on the wall such as an invertebrate, or maybe even a gecko, that might have prompted this behaviour, and wonder what it was IB saw and/or wanted to catch.

08 - juveniles at play

IA and IB sat on the power line this morning at dawn, singing and preening. The brown colouring of the immatures is clearly visible.
I did not see or hear any adults. As far as I remember, IA and IB only voice this particular song (an audio recording can be found on day '07') when the adults are not around, and I wonder whether their songs are a practice to address future territorial disputes, reinforcing their territory as the dominant male does whenever he is sitting on the power pole. Maybe the immatures are even 'forbidden' to utter any calls other than begging for food when the parents are around. Further observations may provide a provisional answer / theory.

Later in the morning I took the photographs below of IA foraging in the garden. I wonder why the magpies wipe their beaks on the grass, and at times on the palm tree stump. Is it to clean their beaks and to sharpen their beaks? A quick google has not brought up a scientific explanation. I will take a video of this beak wiping soon.

Magpies are extremely playful, as was shown on the youtube video that I posted on day '05'. We can easily picture bear or lion cubs playing, and associate play with mammals honing the survival skills that they will need in their adult life, but magpies are very playful too. I have not seen them play hide-and-seek yet, but have observed IA and IB playing shortly after IA's foot had been released from the fishing wire, and before IB entangled his foot. They were rolling around on the ground, pulling on each other's wings, play fighting, and running after each other. I hope that I will see something similar again soon, and maybe even get a chance to video it.

I just googled Australian magpie behaviour and came across a post called Play behaviour of Australian Magpie  . This blog includes some great pictures that illustrate magpie playfulness. It looks very similar to IA's and IB's play that I observed a couple of months back.

07 - magpie song audio

This morning I recorded some magpie calls. The *.wav audio is embedded below and can be downloaded by right-clicking on this link . I have also converted this file for download to an iTunes ringtone . Enjoy! More soon.

06 - magpie song video

IA and IB were foraging in the garden this morning and then IB flew off into a tree, while IA did some more foraging in the neighbours' yard.

I managed to record some of their calls: the video starts with PB sitting on the power line and calling, then there is IB responding from a nearby tree - IA can be heard answering - and it closes with PB calling again. 

05 - playful: youtube video

No observations to report today, just a few fleeting sightings and I heard magpie calls early this morning, but did not see any birds.

More tomorrow. For now, to start the weekend off with some light entertainment, here is a video that I found on youtube. It shows a particularly playful magpie. The url is https://www.youtube.com/watch?v=qoaEBb4IN4Q

04 - magpie family

This morning, around 6:30am, I spotted the entire family on the power pole and quickly took a photograph (another blurry one, I will have to set up a camera with tripod one of these days ...) before rushing off. It is great to see PB again, second from right.

The magpies were not around late afternoon. I will try to make some time over the coming weekend to observe them, and will be thinking about a simple field experiment that I could do to find out about their strategy with regards to resource defence and/or resource sharing.

03 - foraging videos

Yesterday I left home before dawn and got back after dusk, so I did not hear or see the magpies, but this morning at 6:30am IA, IB, and PA sat on the power pole singing, and then the juveniles flew down to forage in the street and the front garden, while PA took off in another direction.

I finished this week's study materials and watched the videos about resource competition on the train yesterday, and am going to devise a simple test to see if and what kind of competition there might be, when the magpie parents come around again 
(I have not seen PB for a while, and PA is not around much either), and/or when other species might be competing for food. 

We learned that there are three types of strategies with regard to competition for resources:
- exploitative competition: this occurs when consumption of a resource such as food, water, space, mates, etc makes the resource unavailable to others within or outside of the species
- resource defence: this is a strategy that makes sense if the costs for monopolisation of a resource are smaller than the benefits reaped
- resource sharing: this is the best strategy if cooperation reduces cost of territoriality

A few months ago, when I was feeding IA and IB, so I could catch them and snip off the fishing line they had entangled around their respective feet, there rarely was competition between the juveniles over the strips of meat on the saucer, even though on one occasion IA uttered a song that must have been territorial, as IB backed off until IA had a good feed. I have also observed them calling each other when food was around, and leaving a scrap or two for the late arrival.
Whenever the parents were around, there was a clear hierarchy, with PA being the first to choose, and then PB could take a feed. PA picked on the juveniles, especially IB who was a bit cheeky and tried to get the first scrap quickly, before PA could get to it. Whenever PA pecked at IB, the juvenile turned on his back in a submissive position. I only saw a peck in IA's direction once from PA, and IA quickly went to hide under one of the chairs outside, and puffed itself up while sitting close to the ground, rather than taking the submissive posture.

So when IA came into the garden early this morning, with IB not far behind, I used some seeds to test whether the siblings would compete for these. The video is below.

As you can see they seem to be quite comfortable sharing, and it was also interesting to observe the juveniles' reaction to various bird calls in the second half of the video. I could not see the parent birds, but IA and IB seemed to react to one set of calls in particular.

Just a few seconds after IA had flown off, I saw what had gotten IB's attention earlier. So here below is a clip where you can see another species, a pied butcherbird (Cracticus nigrogularis), coming into the picture. You can also see IA making a cameo appearance at the beginning, before setting off to forage for worms around the corner. Butcherbirds and magpies belong to the same Cracticidae family and are closely related.

02 - IA behaviour, colouring

It is a cool, sunny morning, and the magpies started their song around 6am. One bird was leading and others joined in. This is called carolling and is often heard as a chorus at dawn. I have observed this magpie family carolling very loudly when they chased off other magpies that had intruded into their territory.

I will record their song soon. For now, as a placeholder, here is a link to a recording that I found on freesound: http://www.freesound.org/people/digifishmusic/sounds/42189/

IA and IB were foraging on the road for insects and their larvae, before flying up to sit on a power polet. The family often perch there, especially IA, IB and PA, the latter often accompanied by a noisy miner (Manorina melanocephala).

When I came out into the garden, IA flew down and sat in front of me, right leg drawn up (see photo below), even though the infection from the fishing wire has long healed and I observe IA skipping about and walking on both legs just like its sibling IB.

I wonder if IA has a memory of the injury from the fishing wire, i.e. if it correlates that time with the food it received, so that this one-legged stance could be a show of 'begging' behaviour to receive its reward. What kind of field experiment could be done to test such a theory?

On this photo you can clearly see the lighter greys and browns that are typical of immature birds. Their plumage turns to the stark black and white of adulthood when they are approximately 3 years old and getting ready to breed for the first time. The female of the race tibicen, common here in SE Queensland, can be distinguished from the male by looking at the top of the mantle at the nape of her neck: it is a mid grey shade rather than the white colour seen in males. The immature birds display the same mid grey colouring at the mantle and at 2-3 years old can be mistaken for females. 

01 - introduction

Last year a pair of magpies built a nest in one of the large trees across the road, and this year their family unit included two young birds. Let's call the immature birds IA and IB, and the adults PA (male) and PB (female).

In March we saw that IA  had fishing wire wound around its right foot. Even though it could only hop on one leg, it was still a great flyer and managed to outwit us each time we tried to catch it. As we did not want to stress it unnecessarily, we decided to call the experts.

First we called Wilvos (Wildlife Volunteers, an Australian institution), and they referred us to the rescue team of Australia Zoo, who have shotgun nets for capture. Unwell koalas and badly injured roos took precedence, but the rescue team called us back and were very helpful, telling us to train IA with food (bacon and mince seemed to be favourites), to enable us to catch it ourselves.

Here is a short video of IA being 'trained'. IA is the puffed up bird on the right, and it has its entangled foot tucked in, and is standing on its left leg. IB stays close to IA as it is after a free feed too.

After a week or so I managed to entice IA into the house and caught it by throwing a large towel over it, and then took it to a local vet who cut off all the thin wire that was entangled around its foot, and put some disinfectant on the wound. I released IA back home and thought that we could now stop feeding the wildlife and enjoy their beautiful song from a distance again.

However, less than a week later, IB had managed to get fishing line entangled around one of its feet too! So out came the bacon again and we managed to catch it within a couple of days, and snipped the fishing line clean off its foot. That was in April, and the actual field notes will start as of tomorrow, 17 June 2014.