Ornithology - Chapter 14

This chapter is about the birds and the bees. Birds do not have X and Y chromosomes like mammals, instead, they have Zs and Ws. ZZ is male, ZW is female. Some evening grosbeaks are male on one side of their bodies and female on the other! Most birds have only one ovary, many raptors have two. And as far as "the act," for most birds, a coital "touch" is all it takes and it takes just a few seconds. And while that seems simple, the formation of the resulting egg is complicated and diverse. Eggs shells range from onion-skin thin to several millimeters thick in ostriches and emus. The color spectrum goes well beyond our human range, with ultraviolet color in eggs that look dull to our eyes. And of course, all birds lay eggs - the very definition of their nature. Pictured above are a male and female goldfinch at the feeder this spring during their molt.

The Current "Read Aloud" to My Daughter

"Fortune's Magic Farm," by Suzann Selfors is the book I'm reading aloud to my daughter right now. It's a story about a 10-year old girl who lives in a place that always rains and nothing grows, except mushrooms between her toes. She's told she was abandoned on a door step when she was a baby and raised by a "grandmother" who soon passes away. Isabelle works full-time at an umbrella factory and lives in a boarding house - and that's pretty much the way everyone lives in this town that never sees the sun. Then, she is "rescued" and told she is heir to a magical place and her magical powers help things grow. We're just up to her rescue in the book. We've learned that elephant seals like to be told their noses are huge and their rear-ends are gigantic. And these "compliments" must be yelled loudly because elephant seals are hard of hearing. The elephant seal is giving Isabelle and Sage, her rescuer, a ride across the ocean.

Chapter 13 - Breeding Systems

Whew! What a complicated diversity of breeding systems. They were the focus of Chapter 13 in "Ornithology," by Frank Gill. The first thing to keep in mind is that raising a brood of chicks requires extended time and energy. A few species have young that don't require too much attention, and the females tend to go it alone raising those chicks. Most birds depend on female and male care to successfully raise the next generation.

And there are some birds who don't bother to raise their own chicks. They're called brood parasites and we know them well: cowbirds and cuckoos. Some bird social systems include cooperate breeding. Assistance birds help breeders while waiting for a chance to raise their own. And something that is found more often than used to be believed is intraspecific brood parasitism - where females of the same species lay eggs in each other's nests while the nest owner isn't looking.

Next up - the "birds and the bees." Pictured above is a female Brewer's blackbird that's been hanging around the front yard.

Mates - Chapter 12 in "Ornithology"

Chapter 12 explored mating habits of birds. I'm reading "Ornithology," by Frank Gill.

You might have heard that most birds choose a mate for life. And that's mostly true, except that doesn't mean the mate is the only father of the chicks. Extra-pair mating is common and is thought to be an avenue for ensuring genetic diversity. It's important for bird couples in most of the world to form a bond because of the time and energy investment in successfully raising a brood. Chicks take a lot of time and care before they're on their own.

A few birds, cowbirds for one, lay their eggs in the nests of other birds and leave the raising to the other bird. And most birds taken advantage of can't tell the difference between their own chicks and the impostors.

Some birds have fancy and complicated mating rituals - from songs and dances, to bower birds, where the male actually constructs a tent and decorates the entry to impress the female.

Pictured above is a pied-billed grebe. I heard a small splash while taking a quick hike in the Hyatt Wetlands and thought I had taken a picture of a turtle. It wasn't until I zoomed in while reviewing the photos later that I realized it was a bird. This is a male. The black stripe on his beak is only around in the spring - to impress the females. Grebes are interesting water birds. They do not have webbed feet like ducks do. And the chicks have to learn to swim. For the first few days, the chicks ride on the backs of their parents.

Chapter 11 - Social Behavior

A solitary red-winged blackbird. You might have noticed they are usually solitary. It's because they don't like to share their space, which is focused on food supply. That was part of the discussion in Chapter Eleven of "Ornithology," by Frank Gill. See earlier posts if you're reading along with me.

Food resources and defense against attack are the two main issues for bird space. Some birds are very territorial about food supplies. Hummingbirds, those sweet little creatures, have dive-bombed me when I've gotten too close to their favorite snacks in my yard. And they chase each other off, as well. That's common for most birds.

Birds that flock together do so mainly for protection against predators. And some birds of mixed species will congregate together and share food - not seeing other species as a threat.

Take a look at a line of birds sitting on a power line. Some species have regimented spaces between each other, others sit closer.

Some birds that are dominant within a species develop different coloring patterns. Those colors are badges to let other birds know they're the boss.

Flocks of birds can be temporary, such as bunching together in flight when a hawk is nearby, or permanent, complex social structures. Some birds of prey hunt in pairs to better their odds.

I spied the blackbird at Hyatt Wetlands in Boise.

Migration - Chapter 10 in "Ornithology"

Migration and navigation are the topics in Chapter 10. I'm reading "Ornithology," by Frank Gill. A fascinating glimpse in this chapter into the took kit birds have when it comes to those topics.

There is no simple explanation of how birds migrate, or navigate. They use sight, read the sun and the stars, forecast the weather, and are sensitive to the earth's magnetic fields. Some even use the natural chemical smells in the air as a guide. Most birds use several of the skills. For example, if the weather is high overcast, above their normal flight altitude, they depend more on magnetic fields than the position of the sun or stars.

Caged migratory species get restless at night when it's their time to migrate. Birds are programmed by nature to get ready to fly. They go on eating binges, too. And while flying, in some cases, thousands of miles, to spend the season sounds like a huge expense of energy, calculations show the investment brings high returns in terms of quality of food sources at the new location, and habitat, and sometimes breeding atmosphere.

Most birds do their big flights at night, and they can be seen on radar. That's why we never "see" them on their routes. Folks who live in flyway zones are more likely to catch glimpses, and some of these air routes converge, especially in stopover locations.

Some birds of the same species migrate while others don't. No good explanation, except they must have decided that the year-round supply of food was adequate.

The bottom line is that scientists don't really know exactly how any bird navigates so well. They've been banded and tracked and many fly thousands of miles and return to the exact same branches of a tree year after year. Some of the knowledge is innate, some of it is learned.

Instances of birds showing up in non-regular territories are likely birds who have lost their navigational skills.

And it's interesting that there are accounts dating back to the 1600s reflecting the belief that birds hibernated - to explain their absence during the cold months in Europe.

The birds pictured above are goldfinches at the thistle feeder yesterday. I first noticed they had returned last week. They spend their winters elsewhere. You can see they're in the process of molting - growing in their bright yellow feathers.

Chapter 9 - Annual Cycles of Birds

Birds are busy! I'm reading "Ornithology," by Frank Gill - just wrapped up Chapter 9 last night. It delved into annual cycles.

Birds have a lot to do every calendar year, and most of them abide by a calendar year for molting, breeding, migrating, intense food-gathering. Because all those things are energy-intensive, they really can't be done at the same time, thus, the "calendar" of annual activity.

Seasons present cycles of stress and opportunity. Birds are guided by internal clocks that can be affected by climate, daylight and food supply.

I found it interesting that when birds are isolated from natural daylight and night, their internal cycles range between 23 and just under 24 hours. Natural daylight and night cues help re-set their internal clocks to match nature's 24-hour cycle.

The bird pictured today is a female pine siskin. She was outside my office window yesterday. The rain didn't stop her from feeding from the black eyed Susan seedheads. I'm sure she's still sticking around here because of abundant food supply from the flower heads, and the thistle feeders in the neighborhood. She will leave at some point to a higher elevation for nesting in pine trees when more food is available there.