Bouncing Boy Blue

So after making a wide range of observations about the behaviour that dinosaurs may have exhibited based upon that observed in birds around my Garden (and longer trying to get it from my notes and on to the blog), it comes time to look at a specific question.

Could there have been bouncing dinosaurs?

What do I mean by bouncing? Well lets look at our little blue star the Superb Fairy Wren. When they move about, they either fly or bounce - they don't walk! On the ground if they move about it is always a two-foot jump, but it looks so effortless that I think of it as bouncing rather than jumping.

Lets have a look at some examples of Mr Blue in action.

Choosing Direction

The Launch - Legs trailing for the push

Regather - Legs pulled up and under

Landed.

Now this seems to happen really fast (tricky to get photos) and is often a series of jumps or bounces from point A to point B.

Lets have a look at another series - this time not in my garden, but on Kangaroo Island in South Australia, observed (and photographed) during a palaeontology field trip in 2013.
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As this fellow is not standing in the grass it is easier to see his legs in action (although a little blurry, sorry). To be honest, there isn't really a lot of leg there - so the bouncing behaviour is not powered by huge muscles in the legs, but must be more about spring and tension in the tendons. His legs are not in exactly the same position; I don't know if this is significant. Perhaps it makes it more of a skip than a jump?

However it is that he manages it, it seems effortless as they can keep it up for ages bobbing here and there in search for food.

So what is "Normal" ground based movement for birds?

Well bipedal locomotion (what we use once we get past crawling) is usually a one foot at a time thing. Like this Raven (photographed on KI at the same time as the Wren above).

Notice that the position of head to body chases as the foot position alters; dinosaurs probably did this too.

So what about the dinosaurs? 

You may remember this species from the Jurassic Park movie franchise, it is called Compsognathus. Unlike many of the dinosaurs portrayed in the film it is about the correct size, equal to that of a chicken. Hesperonychus is another species of similar size as is Scipionyx.

None of these species are large, and all are at least from the same group of dinosaurs birds are descended from, although some are more distant in that lineage. Their mass is fairly light, so could they bounce?

Although about the same size as a chicken they are more lightly built, and well balanced across the hips like the Blue Wren (although the tail feathers make up the counterweight for the body rather that the dinosaur's bony tail). So I think it is a plausible hypothesis, but one that needs some testing.

"Chickens don't bounce" I hear you say... and I'd have to agree with you. Yet the skeleton of a chicken is not as well balanced as that of either the Wren or any of these small carnivorous dinosaurs.

To make the best comparison we would need wren-sized tiny dinosaurs, but as pointed out in the Hesperonychus article linked above, small dinosaurs are absent (for the most part) from the fossil record. We know from looking at modern ecosystems that there are usually many more small critters than large ones; so they should have existed, but due to the nature of the fossilisation process they are unlikely to be preserved.

However that doesn't mean that they weren't there, the same way that we don't know that they didn't bounce... but we can't prove they did either at this stage. Yet without our examination of modern animals it would be impossible to have reconstructed dinosaurs at all, so we study, learn, examine, test, hypothesize and so forth adding new bits of understanding to fill in the picture of the prehistoric past.

Finding Food

Birds eat an amazing variety of different things, and have evolved different strategies to find and eat these foodstuffs.

Sometimes eating is a social occasion to which the whole flock is invited and there is no competition over who eats what. Other times fights break out over who gets which tasty morsel. For some species there is also a tolerance of other species using the same resource.

Our small birds are the ones most often seen feeding together. Thornbills, Wrens, Finches, Robin pair and the Wagtail pair will often be seen in the same place, flocks all mixed up and foraging without being bothered by their neighbours. If one group moves on (especially if startled by the approach of a human with a DSLR bird scarer) the others will take flight to and all resettle in a new location. Of this group, the Wagtails are usually the most mobile, flicking around the group and catching insects on the wing. If the other birds are not around, the Wagtails may use other species to scare up a tasty snack.

Our compost heap contains many tasty treats (from a certain point of view) and the cleanings from the stables which make an excellent home for invertebrates like worms and slaters. Although many of the birds forage around the pile, the most regular visitors are the Ravens and the Magpies. The Ravens seem to be unlikely eaters of the contents of the scrap bucket (vegetable peelings, left over non-meat dinner etc) but they usually arrive to check out what's on offer as soon as the humans have gone away. Usually I dislike having "crows" about as we have had many problems in past years with them attacking newborn lambs and kids (of the goat kind). These seem to have been the other smaller raven species, because once the big pair moved in we stopped having that problem - although they would dispose of any of the other birth remains left lying around. These guys aren't total carnivores as I've seem them take fruit and veg away from the heap.

When the grasses and other seeding plants are ripe the parrots and cockatoos have a picnic. perching delicately upon a stem or convenient fence and nibbling to their heart's content. For the rest of the year they eat a variety of things - at the moment the Sulphur-crested Cockatoos are behaving like rabbits and digging through the grass to get at the roots and possibly grubs.

The noisiest of our visitors - and most dangerous - are the Yellow-tailed Black Cockatoos. The don't live on the farm, but are regular visitors due to the stands of Radiata Pine trees we have planted over the years for livestock shelter. These birds are big, but they aren't aggressive - it's their choice of food which is the danger. They love pinecones eating some in situ, and taking more home to eat later. If they are startled these are likely to be dropped - and hurt if they land upon your head! We will usually hear them coming long before they get here, and they argue over feeding spots while they are here.

These two Cockatoos have found the tasty new growth of the pine trees.

"No, you can't have my spot!"

"You can't have my spot either!"

The noisy group departs with some take-away for later.

Left-overs from a Cockatoo feast.

So like birds, dinosaurs would have eaten a wide variety of things. However this is far easier to study as there are tangible fossil remains in the form of coprolites - fossilised dinosaur droppings. These help us link our observations based on anatomy of what we expect the dinosaurs to have eaten (like tooth shape and jaw shape) with the physical remains or traces in their coprolites. Again it is observations of these things in modern species that make the comparisons possible.

Making a family

Young Male Blue Wren (Superb Fairy Wren)

Looking at the Choughs in my last post made me think about the breeding season for our local birds. Unfortunately it is winter here and the wrong time to be observing these behaviours; too early even for courting as far as I have seen. 

There is still evidence around of the past seasons - young birds growing in to their adult plumage and nests in all shapes and sizes.

Wren? or Thornbill? nest - as it had been abandoned and the eggs undeveloped it is hard to know which species it belongs too. Only the scale narrows it down as these are really small.

Most of our local parrots and cockatoos nest in hollows in standing dead trees like the ones you can see in the paddocks in these images. We can see who is going in and out, but not what goes on inside. Although this year I am contemplating trying to get a closer look but enlisting the aid of my husband's quadcopter with inbuilt camera.

I'd also like to see if anyone comes back to this nest as I don't know who built it.

We did have some obvious successes last season. The Raven pair raised three chicks to adulthood, and the Magpies raised two. The Choughs had a few, as did the Wrens. As none of the other species appear to be in decline, I assume they are breeding too, just not as easy to observe. Although I think these youngsters are taking advantage of their mother; they are as big as she is and still begging for food... 

Then there are the Swallows... I didn't mention them in my species list as they seem too far removed from a native natural species as they seem too reliant upon human created environments. Still they raised too many chicks to fit in their normal roosting spot and have taken up residence in the carport over my car...

The messy mud nest of a Welcome Swallow - would be more welcome not above my laundry door.

So what would a dinosaur nest be like? Perhaps some dinosaurs might make nests off the ground, but this would be difficult for most of them. Did they sit on their eggs to keep them warm like most birds do? Perhaps for some species - we have found fossil nests and eggs. The Oviraptor (meaning egg thief) was a dinosaur discovered alongside a nest of eggs believed to have belonged to another species - Protoceratops. Thus it was thought to be stealing the eggs and so was named for that fact. Later another fossil specimen was discovered over a nest of the same type of eggs, but these had fossils of baby Oviraptors inside them... Thus it was actually nurturing and protecting its eggs rather than stealing them to eat. 

A 75 tonne sauropod (long necked, like Brachiosaurus) is very unlikely to have sat upon her nest - as it would squash under the weight. So either there was no parental care, or it was done without brooding the eggs, perhaps in the manner of Mallee Fowl or Lyrebirds.

Chuffed Companions

The family that works together stays together.

The White-winged Choughs (pronounced chuffs) are another species that has been extensively studied for their behaviours and social interactions. They are social breeders and cooperate to raise the young, who in turn assist to raise their younger siblings.

The family we have here are quite characterful and extreme opportunists. The adults quickly worked out that free food was provided by helpful humans as long as the other big mammals (horses) were kept at a safe distance.

Over the years we have seen them bring their young down an shown them what the colourful containers are that are full of yummy treats, and where the food is placed after that.

Of course this isn't their natural diet, and they are just as dedicated to teaching their young about finding real food too. On occasions we have noticed the young unable to work out how their family got to the other side of a fence and frantically run up and down trying to get through - they seem to forget that they can fly sometimes.

These are photos I took of the group a few days ago - it seemed smaller than I remembered, but this is not the breeding season at the moment so part of the group may have been foraging a little further away.

When I got too close they all scattered for the pine trees above and took up positions facing in different directions. The smallest (I guess youngest) three huddled together and the adult birds spread out around them.

One of the curious things about these birds is that they have whiskers; tiny little hair-like feathers around their nostrils and the base of their beak. These seem to help locate food as the Choughs forage through the litter under the trees.

Choughs never seem to forage with other species, they stick together as a family unit - and will defend the area they've staked out as their spot at that particular instant. The biggest fights I've witnessed are between the other common black & white bird in the area, the Australian Magpie. These can be very heated arguments both physically and vocally from both species.

Dressed for Success

Why is it that some animals evolve to be as uncamouflaged as possible? Display colouration and plumage for sexual selection seems to be more important in some avian species that the need to be hidden from predators. Does that mean the these species are immune to the danger of predation? Or simply that passing on the genetic heritage is a more important factor to be dealt with before death by whatever means?

Flocking behaviours do reduce the likelyhood of any one individual becoming prey through shared vigilance and flock distraction behaviour, but not all birds that exhibit these attractive displays are social creatures.

For example the Cassowary in a flightless bird that lives in a forested environment in the Tropics of Australia and New Guinea. The male has an amazingly colourful head with a crest on the top of his skull. There are few natural predators to this species and, as discussed previously, it is well protected. The bright colour increases the chance that a potential mate will see him through the dense foliage, and also bears striking colour similarity to some of the Cassowary's favourite food.

Our little Blue Wren is dressed in a similar colour, but not to match food this time. His bright colour is a signal to his family and is obvious to any potential interloper that this is a "taken" group of females. the only times I have seen a second male with the groups around here is when a young male is almost completely decked out in his adult colouring - I haven't seen any visiting males, nor the moment when the young male is sent from the group.

Quite often there is a colour difference between the male and female of the same species as you can see above with the blue wrens and below with the Red-rumped Parrot. Until recently I thought that the bright male was the only option and that females were never more colourful than their companions, however there are apparently a few species like the Eclectus Parrot that break this rule.

The brightest local bird is probably the Crimson Rosella, a stand-out against all the local foliage. These birds are usually found in pairs or as a flock of juveniles (with slightly different colouration).

Given that the feathers I found when following the Sparrowhawks (see Predators 2) were brightly coloured, and that there is never an absence or obvious fluctuation in the numbers of these brightly coloured birds, their breeding must be successful enough to maintain a stable population.

So what can we draw from this for our reconstructions of the Dinosaurian ancestors? We have found many species that exhibit physical sexual dimorphism in their physical forms - particularly the crested Hadrosaurs and horned Ceratopsians. It is also a possibility that dinosaurs came in the same spectrum of colours as birds do today. It is not necessary for them all to have been uniform grey like elephants or camouflaged like many birds. Bright displays of colour are plausible for dinosaurs too, although there is yet to be fossil evidence to support them being as bright as the Blue Wren or Rosella. We do some evidence from dinosaur feathers to support colour variation across the body including stripes and different colours in different body areas. 

How not to be seen

The colour of dinosaurs is always a matter of discussion when reconstructions are being planned. Until some of the recent feathered dinosaur fossils were discovered there was virtually no evidence for what colour they were. Again we must observe living species to see how their colours work with their environment and draw comparisons to apply to the dinosaurs.

Species generally fit into two categories, predators and prey (or diners and dinner). Obviously it is good to be the predator and not worry too much about being someone's dinner. For the prey species, usually herbivores, it works out best if someone else is eaten... then you survive to maybe pass on your genetic heritage. So how do you reduce the chance of being food? 

Birds (Aves) are on the far left of the cladeogram. The red part is all carnivores except for the first branch - Sauropods, which are the giant long-necked herbivores.

Our Bird descendants do not possess the variety of spiked or armoured protective adornments that some

dinosaurs did (for a number of reasons, but mostly as these dinosaurs are not their direct ancestors - the carnivorous dinosaurs are). Instead they have the power of flight to try and evade capture, or the ability to blend in to their environments and hopefully avoid detection (camouflage), or flocking behaviour to play the numbers game.

So lets have a look at "How not to bee Seen".

How many birds can you find in this patch of "lawn"? 

There is only one bird in this image, but again it doesn't stand out.

Again this pigeon blends in pretty well although it has chosen a rather obvious position to perch.

This example is more obvious, but is using counter-shading instead of camouflage. From above the dark blends with the trees and ground, from below the belly blends with the light from the sky. This strategy is used by many species including mammals and fish.

While these ones don't really blend in at all. instead they must rely on other active strategies to avoid predators.

Camouflage is passive - it doesn't require any effort to use apart from the initial expense of growing the pattern/plumage/scales in the first place. In birds it is not adaptive (although countershading is more so) and against the wrong background it doesn't work. However for the most part it is an effective strategy and thus we would expect it to be used by many dinosaur species.

So why do some animals, like the Rosellas above go to the opposite extreme and did dinosaurs do that too?... well that's another story.

Non-verbal Communication - Squeeky Pigeons

The Crested Pigeon Ocyphaps lophotes is a bit of a show off when it comes to socialising, but doesn't make a huge variety of vocalisations when compared to other species including the Blue Wrens.


During courtship the males tend to be content with strutting, bobbing up and down and cooing while fanning out their tails.

But it is their alarm call - the non-vocal warning that makes them stand out among all the inhabitants of the Garden. This noise is generated by their wing feathers vibrating against the air. 

I wonder if there was a way that dinosaurs could use non verbal signals like this? Perhaps a tail slap or whip crack from a long-tailed sauropod (like Diplodocus), stomping feet and vibrations? This is a puzzle just waiting to be solved.

Predators 2 - Or Did T-rex Roar?

Often when I'm out visiting kids to talk about dinosaurs I get them to pretend to be different types. Now none of these kids have ever seen one of these as a living creature, so it is the collected information from books and other media that they use to build their image of what they were like. When we get to T-rex (a large predatory dinosaur with big teeth and short arms) the children almost always get really noisy roaring to show how fierce they are. It takes a bit to convince them that a noisy T-rex is going to be a hungry one as all his food will hear him coming and hide to avoid being dinner.

This makes a lot of sense and can be backed up by observations of modern animals hunting; being usually stealthy and quiet in the process. Usually once the kids think about it they can understand - but they still like to Roar! Dinosaurs may indeed have Roared, but perhaps not all the time.

I was surprised to hear an unusual bird call a little while ago, a repeated chirruping sound that did not belong to one of my local residents. I grabbed my camera and went out to look for the animal responsible and was very surprised by what I found.

You can hear the sound mixed with some Galahs in the link on this page from the Canberra Ornithologists Group - Collared Sparrowhawk.

He was hunting within the trees that are on a little hill quite close to the Garden - many of our locals go there for food and shelter. 

It took a bit to find him, and I'd have failed totally if hadn't been so noisy. Eventually I tracked where he had perched and was able to get a few photos (ok quite a lot of photos as I inched closer, but I won't bore you with all of them). He occasionally flew off calling, but returned to the same place. On the ground in a few places I could see clumps of bright feathers from Eastern Rosellas and another clump of black & white ones probably from a Pee-wee or young Magpie.

Young Male Collared Sparrowhawk - for some reason he preferred to perch on one leg. Occasionally he would call, but I didn't ever hear a reply.

 It wasn't until the light had almost gone and I was about to give up that I saw his partner. She was larger and less banded, and never made a sound. I only noticed her because he flew toward her from his dead tree location above and landed just so that they couldn't be photographed together.

I looked them up later to find out more and learnt that it was a young male (shape of tail and colour) and a mature female. I don't know if they were a pair or a parent teaching a youngster. The thought that did occur to me then was that they might have a joint hunting strategy. One noisy "Look out I'm hungry and hunting over here" while the other silently grabs the unsuspecting prey in a slightly different location or from another direction.  Alternately he might just not be very good at the being quiet thing (like most kids).

While I was walking through the trees, the Blue Wrens seemed undisturbed by the pair of raptors, but from the size of the feather piles I guess they were in the "not big enough to eat" category.

Can you see the Dinosaurs?

Now I didn't take all these photos in my garden, but I wanted to illustrate some of the similarities between the extinct dinosaurs and their living avian descendants. The  first 4 photos were taken at Taronga Zoo in Sydney, The Raven at Kangaroo Island in South Australia and the last 2 on my farm.

Firstly lets have a look at the legs on these avian dinosaurs or birds as we commonly call them.

Our first example is probably the most dangerous pair of dinosaur-like legs to be strutting around these days. Although the Cassowary is not carnivorous, it does possess a huge claw on the inner toe of each foot. This toe is only half as long as the others (in a skeletal sense) but makes up the rest of its length with a strong sharp claw. Althought this is primarily a defence mechanism, it is powerful enough to punch through corrugated iron or squishy people who get too close. Several dinosaurs also had a claw adaption like this including the Velociraptor.

More important than the claw, is the position of the legs. All dinosaurs have their legs directly underneath their bodies, regardless of whether they are walking on two legs or four. Birds and mammals have the same style of leg structure. 

Another feature of the Cassowary is the striking colour usage - but I'll come back to that in another post.

This charming Emu was very obliging for his closeup shots (I was drumming to him as he drummed - vocalised - which attracted his attention, hopefully I can talk about sounds later too).

People often have the image in their minds that birds are covered in feathers - and for most of their bodies that is pretty accurate, although feathers can vary widely across species. The Emu is flightless and so does not need the stiff plumage of a bird such as the Raven below. Instead some of the feathers are mere filaments - almost wispy hairs with the skin visible beneath them. There have now been many dinosaur fossils found that include the impressions of feathers around the skeleton, much like those you can see here. The beak area and legs are usually without feathers and much more like those of their ancestors.

Apart from the tail being made up of long feathers attached to a stubby tail instead of a long bony tail, there is a lot about the silhouette of this Raven that makes me thing of small predatory dinosaurs. This is the real purpose behind all these ramblings. There is so much we cannot tell from simply looking at the fossils themselves, but when we look at analogues and descendants of those animals we can begin to fill in the gaps and bring the extinct dinosaurs to life. Watching this fellow strut across the carpark towards the trees, watching for threats and opportunities (like dropped food), it was very easy to imagine a small omnivorous dinosaur doing the same millions of years ago.

Dinosaurs and Birds both lay eggs with hard shells. These tiny beauties were found in the garden inside an old animal transport cage that had been forgotten in the grass. I don't yet know who they belonged to, but the eggs were not fertile or fresh. The nest composition is grass, horse hair and soft cashmere from our goats. Dinosaur nests have also been found fossilised, although often it is the hard eggs only, rather than the composition material of the nest. Again we can make observations of existing species that help up put dinosaur discoveries into perspective. In Montana, USA a discovery was made of many giant nests, each with multiple eggs and located about 12m away from each other. The distance was about the length of one of the adults of this species - Maiasaura, and the area may have looked like a colony of giant seagulls nesting together. Inside the nest was plant material, perhaps what the parents brought for their chicks to eat. How do we know that? Skeletons of newly hatched or almost hatched baby dinosaurs were also found and their skeletons were not developed enough to allow them to leave the nest immediately and fend for themselves - they needed parental care - like many modern birds. Eggshell was also found crushed into the bottoms of the nest - an indicator of chicks moving about within the confines of their safe brooding area.

Moving about in groups while foraging is a strategy we have seen mentioned often during our lectures, and there are many reasons for it. We have fossilised footprints and trackways that show some dinosaurs also did this too. Although these Cockatoos do spend some time wandering on the ground like their ancestors, their ability to fly off in a time of danger means we are less likely to find footprints of them. You can see where they have been though - if you look closely at the image you can see little brown dots - these are the tufts of grass that have been pulled up as the birds search for tasty roots to eat (or at least I think that's what they are eating).

I hope this ramble helps to illustrate some of the reasons for this blog and unusual focus for a study of animal behaviour.