A ruminant bird? meet the Hoatzin

This incredible bird is unique for several major reasons, least of which is its incredible plumage!  I decided to illustrate perhaps the most intriguing aspect of its anatomy…its foregut.  This bird is unique for its huge crop, which makes up 25% of its body weight.  Normally in birds edibles are digested relatively swiftly in the hindgut, but the hoatzin has this enlarged crop that is basically a big vat of fermentation and microbial breakdown stuffed with stinky leaves.  It may retain the leaves for 1-2 days, and the hoatzin spends much of its time stooped over, waiting for the slow release of the nutrients.  The crop is in fact so important, evolutionarily speaking, that theflight muscles and associated keel and sternum have both been reduced to give it more space!  It is consequently a weak flyer.

While I am on the subject, lets talk about other hoatzin oddities.  The chicks when born have a little clawed hand to go foraging among the trees when its parents are away!  It is also a way for them to avoid danger as the nests are set up over water, so that when a threat comes the chick drops into the water, and later climbs back to safety when the coast is clear.  A vestige of its dinosaur lineage?  Interestingly coots also have little single claws on their upper appendages too.

Here is an image composite I created showing what is digital and what is the base painting.  I first found some reference images taken at an upward angle.  I made a prelim sketch, resized it for the illlustration board I planned to use, transferred the lines, touched up the lines further in graphite, then began painting it all in gouache, laying it down light in the beginning, and working darker and darker.  But what this image shows is how much mileage I got out of the digital side of the rendering.  As you can see the sternum and crop have many levels of opacity interplay, so sweet with digital.  But especially feathering some of the feathers made it a lot softer and downy looking.

Let me know what you think!

the poetic precision of a leaping salticid (aka jumping spider)

I did this image of a salticid, (also known as a jumping spider), in mid flight. What is coolest about it is that it is from a vantage point that you could never really photograph.   They are one of the many cool spiders that DO NOT make webs to catch prey, but are inquisitive, extremely intelligent, active hunters that launch themselves airborne onto their unsuspecting prey.

Don’t get me wrong, I love my web-bound spiders.  But that they normally rely on vibrations and not visual cues means that evolution has dealt them a hand of very poor vision.  Salticids, at the opposite end of the spectrum, have evolved one of their pairs of “median” eyes to become greatly enlarged, so they have incredible vision.  While jumping spiders cannot move their whole eyes independently, they can move the retinas of their Anterior Median eyes.  They cannot focus, but their movable retinas  increase their field of vision.

They are also known for their deft ability to learn and solve problems in approaching prey.  Often in search of the best angle to approach their unsuspecting prey,  salticids, (specifically Portias) have been observed taking such far flung routes to reach the prey that they break visual contact with it!   check out this wikipedia description on Portias:   http://en.wikipedia.org/wiki/Portia_%28genus%29

In making this illustration, the most difficult part was figuring out the posture of the legs.  You can imagine how impossible it is to observe a jumping spider in mid-flight…just watching one move from place to place, it happens so fast you never even see the inbetween, just poof! and its on the next leaf.  I am lucky enough to have captured a partial stereo image of a jumping spider jumping toward the lens bracket of my macro camera!  So I was able to use it, and other generalized illustrations, like in Rainier Foelix’s book on spiders, to come up with this illustration.  I loved doing it, and hope to illustrate many more salticids.