Friday, August 9, 2019

Chapter 3: How Birds Evolve

So, like I mentioned before, I'll be moving quickly through these chapters to meet my deadline. Full disclosure: I am NOT reading, taking quizzes, sketching, and posting as quickly as it looks.

The chapters are definitely getting longer and more thorough. This chapter covered natural and sexual selection, speciation, hybridization, divergence of bird populations, and adaptive radiations of birds. Without going into the nitty-gritty details of the entire section, here are a few highlights that caught my attention:

Cornell Lab of Ornithology: Handbook of Bird Biology, Third Ed. Chapter 3, page 64-65
Most people are familiar with the common household pet Budgerigars, or parakeet, and I am not an exception. In fact, I have a pet Budgie right now named Kiwi who I've cared for about 12 years. In the section above detailing the four conditions for natural selection, there is a small box (3.01) that details on how each bird has their own unique traits to that particular individual. The photo they show in the book makes it difficult to determine each individual budgie in a giant flock, but it made me look really closely at Kiwi to see if I could determine some of her own unique characteristics. You can tell her dad was a typically colored budgie, but her mom was a blue/white coloring, lacking the yellow pigment in her feathers. Maybe I can't see what other birds see, but she's cute to look at regardless!

Kiwi, my budgie, on her swing! 💚

While the information in the book is really useful and relevant to the bird biology course, sometimes I feel like I am gaining more value in simply learning about new species that I have never seen or heard about. For example, in the section regarding sexual selection, this photo of a nighthawk from the savannas of central Africa caught my attention:

Cornell Lab of Ornithology: Handbook of Bird Biology, Third Ed. Chapter 3, top of page 71
You have to look closely to see what is written in the caption, but these nighthawks have developed flag-like extension of their secondary flight feathers for attracting mates. Obviously, this beautiful trait can be cumbersome to bird that relies on catching insects on the wing, but HOW COOL! I had to look up some more images of them to see the ornamental feathers in flight and sketch my findings.

Standard-winged Nighthawks in Flight sketch, 9x12, graphite on paper
Speciation is the evolutionary process by which one ancestral lineage splits into two or more descendants species. The book describes how allopatric speciation (speciation in populations that occur in separate regions with no geographic overlap) probably caused the divergence of certain hummingbird species in South America's mainland and islands. While not specifically mentioned in the text, it reminded me how hummingbirds are a definitive species of the Americas, not found on any other continent across the globe. Makes our native Ruby-throated Hummingbirds here in NW Indiana seem pretty special, so I found a great image reference and sketched one. I think I might turn it into a painting.
Ruby-throated Hummingbird (female) in flight sketch, 9x12, graphite on paper
Chapter 4 is on Feathers and Plumages-- Stay tuned for more sketches and notes!

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