There are two types of young

PRECOCIAL--are covered with down; eyes open, alert; legs strong, can walk in few hours; nest on ground, almost never in trees.

ALTRICIAL-- naked, can't regulate temperature; eyes closed at hatching; weak, can't stand up; mouth lining variable, often conspicuous, bright; nesting is variable, all tree nesters are altricial except the Hoatzin.

There is really a gradient from precocial to altricial.



Northern Waterthrush

Comments

Post a Comment

Popular posts from this blog

Goals and Supplies

Birding's beauty is that it only takes a field guide and a pair of binoculars--WHICH IS ALL YOU NEED, AT LEAST 7x35, (but 8x or 10x are better; the second number is your field of vision, so a big number there is a good thing), walking shoes and old clothes. More on these subjects are covered in the concluding remarks section of this course. If you are interested, two exellent ornithology texts are Gill's Ornithology , published by Freeman and Welty's The Life of Birds . Current students have a rudimentary textbook embedded in their CD-ROM. Thayer's Birds of North America . THE GOALS OF THIS COURSE ARE TWO FOLD: 1) to enhance your appreciation of birds. 2) to encourage you to make observations or investigations of your own. My name is Dan Tallman . I am an ornithologist by training. I will try to keep unnecessary technical terms out of this course, which is often hard for someone who is completely immersed in his or her scientific field. But, hopefully, as a birder by h...
Read more

Ornithology

Image
 Song Sparrow What can ornithology do for you? Why study it? In no other branch of science have amateurs played such an important role: Margaret Nice's Life History of the Song Sparrow is a classic example. My students have written papers in their state bird journal . But I don't mean to make you all into scientists. Bird watching (birding) is a hobby for many and a passion for some. Housewives (and even househusbands) trapped at home find an outlet by keeping track of the varieties of birds at outdoor feeders. You'll never get bored traveling between cities to--you may even enjoy the trip. Trips across the country become down-right exciting as you search for and find new and different species. You become more in tune with the world, our ecosystem.
Read more

Introduction

Image
This ornithology course originated from lecture notes that I developed over the years. I have retired from teaching and see little reason to have this resouce, such as it is, gather dust in some drawer. In this blog format, I offer it to you as a free, non-credit, self-study exercise.  As such, you many expect little or no interaction from me (although I will be glad to hear about possible editorial improvements). This blog is not intended as an all-inclusive course. For example, I also taught courses in Ecology and Evolution, so many fundamental aspects of those courses are not found here. It would be wise, then, to have a General Biology textbook, in case something is not fully explained here. I expected students taking this course to purchase an ornithology textbook. Later, students bought Thayer's CD-ROM disk, Birds of North America, that has a brief textbook embedded within it. Either way, you can go into various subjects in more depth or check out areas that may be neglected...
Read more