At least two turtle species live in my stock ponds near the northernmost stretch of perennial flow in the Agua Fria River.  I am sure Texas Spiny Softshells and Pond Sliders (photo) are present.  I think I saw a Sonoran Mud turtle, but the individual I saw might have been a small Pond Slider.

Turtles have exceptional regenerative powers.  Dr. Justin Congdon, a classmate from long ago, managed a study of turtles in the E. S. George Reserve in Michigan for more than 40 years. In the 1980’s Justin made a startling discovery:  Blanding’s Turtles were producing more eggs and offspring as they got older.  Eventually Justin published his results and drew international attention.

Related research shows that turtle cells live longer than cells of  most other vertebrates.  Learning how they do it might provide a means to add as much as 100 years to the average human lifespan. Continue reading →

Click here for the latest Arizona mammal update.

Arizona’s premier mammal species, and one of the very youngest, the humans (Homo sapiens), congregates in urban habitats that most other mammals avoid.  Residents of the scattered human homes of the Agua Fria River Basin often see the 15 to 20 common species that are active during the day and early evening.  Residents of large urban areas such as Phoenix and Tucson rarely see more than three or four species.

Developers are eager to fill the Agua Fria River Basin with homes and businesses.  As the human population of the Basin grows, the number of familiar mammals will decline.

Of course, almost all species decline as the human population grows.  When I began high school in 1960, the human population of earth totaled three billion.  Forty years later in 2000, it had doubled.  From 1960 to 2000 the U. S. population grew from 180 million to 280 million, and will add more than 100 million during the next 25 years.

In Arizona the extinction of other species by humans is occurring most rapidly for species that spend much of their lives in or near water (look at the blog posts on fish and amphibians).  This is because toxic wastes flow down slope to the streams and lakes, and because the streams and lakes are being modified.  Over the next 100 years many species will disappear.  Mass extinctions have occurred before in Earth’s history, but it is likely that none were as large or sudden as the one that is being caused now by humans.  Certainly no other single species has ever achieved such a great destruction of life on earth.

Mammals are described in numerous field guides and websites (e.g., Kays and Wilson, 2002, National Wildlife Federation, AZGDF).  Field guides often illustrate animal tracks, and some (e.g., Halfpenny 2000) are devoted to this essential subject.  A complete field guide to Arizona’s 144 mammal species can be assembled and downloaded from the North American Mammals page of the Smithsonian Institution’s National Museum of Natural History web site.  The downloaded field guide will have a page for each species with a picture, distribution map, and description.

The photograph shows a Rock Squirrel sitting on a fence post.  Continue reading →