Courtship and Mating

Read about bowerbirds in your text, since I will not cover them here. Courtship is fairly descriptive natural history--it's amazing how much remains to be done. We watched Vermillion Flycatchers in Arizona court, only to read a paper on it the next year in a national journal. Their courtship had not been officially described when we watched them! I will limit this lecture to a discussion of pair-bonds.

There are 3 types:
1. monogamy (90% of birds) 1 male; 1 female. Usually for one season but sometimes permanent in long-lived species that are either nonmigratory or that winter together. Some albatrosses always come back to exactly the same spot.
2. polygamy (9%), Lasting pair bonds with a) polygyny = 1 male + 2 females; b) polyandry = 1 female + 2 males
3. promiscuity (1%) These birds are either random maters or form leks.
 
Once birds court, they then begin NESTING.


Northern Jacana

Comments

Post a Comment

Popular posts from this blog

Origin and Evolution of Birds

What was our definition of a bird? Many modern vertebrate zoologists would change that to: "reptiles with feathers." Indeed, one researcher claims that birds are all that is left over from the dinosaurs--he holds for various reasons that many dinosaurs were warm-blooded. It could be that we don't have bird feeders but dinosaur feeders in our backyards. There should be a lot of material on the Internet on birds and dinosaurs. Try Googling the debate. In any case, reptiles and birds (esp. crocodiles and birds) share a great number of features--so many that there can be little doubt but that they are closely related to the point that they once shared common ancestors. This common ancestor is thought to be THECODONT dinosaurs back in the TRIASSIC period of the geologic time scale 225 million years ago. (I once asked for the geologic time scale for extra credit-another mark of an educated person.) 1) skeletons similar: joints between skull and jaw the same in crocs and birds; ...
Read more

Birding

Image
Bald Eagle During this course I expect you to keep a life list of the birds you see--either in the book or on a checklist. Of course, if you keep it up after the course is over is up to you. Many birders keep a life list of species seen throughout their whole lives. I keep track of the dates and places all around the world. (Some people are into cathedrals and Rembrandt's but I race out to the nearest swamp!) If you keep up birding seriously, you might want to start a Year List in addition to a life list, monthly lists state lists, big days, world lists, semesters, country lists, Christmas counts, spring counts are all examples of lists people keep. Birding can quickly become a sport that can involve any number of players. The South Dakota Ornithologists' Union saw 150 species in one weekend in Sisseton, South Dakota. The sport can be costly too--once friends saw a Bald Eagle and jumped out of their jeep. Unfortunately, nobody turned the jeep off, so it proceeded into a lake!...
Read more

Eggs

Image
All birds lay hard-shelled eggs--none give birth to live young because of weight problems. Try to find a diagram of the female reproductive system and what happens where and when (it takes 24-48 hr. = follicle to vagina): Facts to note are that fertilization occurs in the ovary. When the follicle ruptures, the ovum starts down the oviduct and consists only of yolk and embreyo. Egg white is added in the oviduct. Albumen and the egg membrane are added in the isthmus. Finally in the uterus the egg shell and pigment are added. All this takes a tremendous amount of energy (?) (classically assumed, anyway: time of molt may actually be much more critical). (Never hassle molting chickens--they are liable to go into shock). If young Blue-footed Boobies leave the guano circle around the "nest," the young are ignored by the parent and the young starve.
Read more