Centennial Resurvey of the San Jacinto Mountains

Chris & Marilyn-- Centennial Resurvey of the San Jacinto Mountains, California

Presentation

This family project is a whole-family venture, including ancestors! The goal is to look at a mountain range, and reveal how the wildlife have changed over the years.

Chris: Joe Grinnell was a collector, author, and museum director. Harry Swarth, Chris’ grandfather, worked with him. Many specimens were collected and preserved. All the information is online along with field notes, which were so complete that it’s possible to go back to the exact sites they visited. Left a legacy of studies that show that certain species are found in certain zones at certain elevations and are also different on the east and west sides of the mountain. Highest point, San Jacinto Peak: 10,834 feet high. Adjacent to “serious desert.”

Some of the same palm trees are visible in contemporary photos that were there 100 years ago. Chris and his family camped—it is not all built up in the mountains! They caught/trapped birds and mammals, done exactly as they did it in 1908. For some, they only needed to collect a feather, then let them go. Organs were collected for preservation. Mountains go from a low of 750 feet.

Resurvey goals:

· Replication

· New baseline

Several species were seen to have gone extinct or are almost extirpated; about three times as many new ones have appeared.

Burrowing Owls are in terrible declines, not because of anything specific in the mountains, but as part of a wider trends. There are many urban-expanding species. At the Museum of Vertebrate Zoology, they allowed a little removal of specimen to compare.

Marilyn: Birds have experienced a change in habitat. Does elevation explain any trends in stable isotopes of carbon and nitrogen? How about trophic levels?

Everything is warmer by half to three degrees (winter-summer). There’s a general trend that it’s drier at higher elevations. Hypothesis: As the climate warms, species are going to migrate up to where the climate is cooler. A study found that a chipmunk population went up, as did the Mountain Quail. Some didn’t change or went down, so it’s not consistent.

Stable isotopes: between 1908 and 2008: There is a statistical difference in CO2 concentration effects. If we compare plants that were collected on the eastern slope from the western there is also a difference. The pollution might be blowing in from Los Angeles and impacting the west more.

Remember . . . you are what you eat PLUS . . .

• The insects are key to avian diet


• Insects were not a part of sampling in 1908, so they were not collected.

Analysis shows that birds had different carbon and nitrogen isotopes. The majority of them were actually feeding at a different trophic level. Historically, in 1908, the birds could live off different diets, whereas now sources have been condensed, and remaining wildlife will have to have adapted their diet. All the nitrogen data was significant, which means that the protein sources were different.

Carbon sources have changed; climate, environment or diet? These birds have shifted their trophic level upwards, which means that insects have become a more predominant food source. This raises a question about how the vegetation has changed.

Many agencies and organizations are cooperating. This project shows how important preserving collections can be. Today, scientists can use tissue from specimens to learn about relationships between species, and for conservation and understanding the impacts to species. The field notes that Grinnell and Swarth took are also very valuable. There have been no other projects to attempt so much.