Paying Jobs and No Time

Dear Friends --

The paying jobs I've been working on recently are leaving me with little time for blogging.  But look for a post on the sea otters of the Channel Islands soon!  (Really!)

MacArthur and Wilson II: Archipelagos

Last weekend, my post outlined MacArthur and Wilson's Theory of Island Biogeography for one island. Recall that we discussed on how islands gained species, through colonization, and how they lost species, through extinction.

But islands often occur as part of an archipelago, a collection of islands. Islands in the archipelago vary in a number of ways, including topography, shape, size, and distance to the mainland. MacArthur and Wilson focused on the effect that two characteristics affect diversity: distance between the island and the mainland, and island size.

The Island Scrub Jay -- Cause for Concern

Painting by Eli W. Blake Jr.
December 1886
(From Collins 2009)

The Island scrub jay (Aphelocoma insularis) is found only on Santa Cruz Island, the largest of the eight California Channel Islands. It is the only bird island endemic in the continental United States. (An endemic is a species unique to one location and found nowhere else.) Estimates of the population size for Island scrub jays has varied over time and between studies. Generally speaking, older studies estimated a larger population size than more recent studies, suggesting that the population has declined.

Wildlife biologists studying the birds cannot confirm a population decline, but the present-day estimate (2500) is small enough to concern them for several reasons. First, of course, this population is restricted to a single island, increasing the likelihood that one catastrophic event (like a fire) could jeopardize the entire species. Quite literally, their eggs are all in one basket! Second, a population size of 2500 is smaller than that of other bird species designated as endangered by the US federal government (e.g. the Red-cockaded woodpecker). A third reason for concern is that when island populations of other species have declined, they have often declined very rapidly, leaving little time for addressing, or even detecting, the decline. 

Island Biogeography & the Channel Islands

E. O. Wilson (top)
Robert H. MacArthur
(below)
(from bioquest.org)

I anticipated posting this weekend about how species get to islands. I will get to that, but I thought that first I should talk about island biogeography. When I was first introduced to this model of island biogeography, I was fairly baffled. I didn't get the swooshing lines. I didn't understand why their intersection was interesting. Over the years, I've had to teach about the model to undergraduates, as both a graduate student and a faculty member. As soon as I understood it, it became one of my favorite concepts to teach!

The Theory of Island Biogeography, published by Robert H. MacArthur and Edward O. Wilson in 1967, is a classic ecological model of island biodiversity. An abbreviated explanation of this model was in the most recent Catalina Island Conservancy online newsletter.

Glidden's Archaeological Archives Uncovered!

Unearthing Catalina History Using Skeleton Clues

This story appeared in the LA Times today about Ralph Glidden, an archaeologist/huckster who lived on the island in the first half of the 20th century.

One of Glidden's notebooks
(Photo by Christina House, from LA Times story)

John Boraggina, the recent curator of the Catalina Island Museum found Glidden's archives in a storage room at the Museum. He was shocked to find that the records point to the locations where Glidden's archaeological finds were made.

Archaeologists have long been troubled by Glidden's collection because he was not above supplementing bona fide artifacts and human remains from Catalina from those he purchased elsewhere. This complicates the historical interpretation of his finds. He operated a "museum" on the island until 1950 and tried to sell the collection after his business closed. The pieces were eventually purchased by the Wrigley Family who in turn donated them to the Catalina Island Museum. The Museum has since placed some of the more important artifacts and remains with the Fowler Museum at UCLA.

Glidden's Catalina Museum of Island Indians
(Photo from tongvapeople.com)

Full citation:
Sagahun, Louis. 1 April 2012. Unearthing Catalina history using skeleton clues. Los Angeles Times. http://www.latimes.com/news/local/la-me-catalina-bones-20120402,0,5531466.story?

Photo credits:
House, Christina -- photo included in the LA Times story.
http://www.tongvapeople.com/island-of-indians.html

Meet "the most interesting bird on the island"

Island scrub jay
(Photo from Channel Islands Restoration site)

"...the most interesting bird on the island" (Howell and van Rossem, 1911)

The Island scrub jay (Aphelocoma insularis), found only on Santa Cruz Island, was first described by scientists in 1886. Its nearest relative is the Western scrub jay (Aphelocoma californica), which is found in the western United States and Mexico. The island species differs morphologically from the mainland species by being larger, brighter blue, and having a larger bill.

A Bibliography of the Channel Islands

I really like books -- reading them, collecting them, and sharing them.

I'm rounding up the titles of as many books as I can find about the Channel Islands. I'll update the page as I refine these entries and add new titles. I am not including books that are solely tourist guides and cruising/diving guidebooks.

Please add to the list in the comments section and let me know what you think of books you've read about the islands -- good, bad, and mediocre.

Page last updated: 27 March 2012

History of Islands: Connection and Isolation

Catalina Island

Not all islands are created equal.

You can't tell at first glance, but the history of an island is one of the key factors that affects biodiversity on the island.

Catalina's Foxes are Back!

A radiocollared Catalina Island Fox
(Urocyon littoralis catalinae)

The first year I lived on Catalina, I rarely saw a Catalina Island Fox -- we felt very lucky when we came across one. But all that has changed. These days we see foxes regularly, even on short trips around the Isthmus. These sightings are exciting – after all, just seven years ago this species was listed as endangered by the US Federal Government.

Anecdotes like ours, in and of themselves, are not convincing evidence that fox populations have recovered on Catalina Island. But our impression that foxes are more abundant is borne out by population estimates made by the Catalina Island Conservancy.  According to a January 19, 2012 LA Times story, there are now 1542 foxes on the island. The Catalina Island fox is back!

Welcome to the American Galapagos!

Nearly everyone knows about the Galapagos Islands -- the islands that inspired Darwin to develop his ideas about natural selection (not exactly true, but not exactly false), natural laboratory of evolution, popular tourist destination.

But not everyone knows that the US has its own Galapagos Islands, the California Channel Islands.

The Channel Islands are a group of eight islands located in the Southern California Bight (the indentation of the coast between Point Conception and San Diego). The islands range from about 12 to 60 miles off the coast. The four Northern Channel Islands are Santa Cruz, Santa Rosa, San Miguel, and Anacapa. The remaining four are considered the Southern Channel Islands: Santa Barbara, Santa Catalina, San Nicolas, and San Clemente.

Five of the islands are owned by the federal government as the Channel Islands National Park (part of Santa Cruz, Santa Rosa, San Miguel, Anacapa, and Santa Barbara). The Nature Conservancy owns the remainder of Santa Cruz Island.

San Nicolas and San Clemente are owned by the US Navy, who use them for training. Santa Catalina Island (usually just called "Catalina") is the only island that is privately owned -- mostly by the Catalina Island Conservancy. This island is my home.

Anacapa Island as seen from Santa Cruz Island
Photo by Lori Nelson

Through this blog, I hope to introduce readers to the Channel Islands -- their natural history, their human history, and what the future might hold for them.

Some posts will talk about individual islands or groups of islands, other posts will describe the biology and ecology of particular species or groups of species.  I'll talk about how the islands are similar to the Galapagos, but important ways in which they differ from that more famous archipelago. The people who lived on the islands were an interesting and daring bunch of people -- I'll have posts about them too!

I hope you have a good time -- I know I will!