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Wednesday, February 29, 2012

Killer Legs: Crab Spider Wins Prize with Eight!

On Sunday, February 26, Museum Educator Anna Holden, and myself took some families out to the North Campus to collect spiders! The spiders were collected so they can be identified and preserved as part of our ongoing L.A. Spider Survey. They will also be added to our ever-growing North Campus species list.

Briana Burrows and Anna Holden
(looks like they really like collecting spiders too)

All told, we collected 17 spiders (not bad for a newly planted habitat) many of which were very small and non-descript think tiny brown specks almost indistinguishable from a piece of dirt (did I mention these children have amazing eyesight?). However, there was one spider that stood out from the crowd. She was large, and yellow, and had oh such lovely legs! Let me introduce you to the Whitebanded Crab Spider, Misumenoides formosipes (her species name is derived from the Latin formosus = beautiful and pes = foot or leg).

Female Whitebanded Crab Spider

This group of spiders is so named for their crab-like appearance and movement. They are adept at quickly moving sideways, backwards, and forwards. This quick movement is only infrequently observed by us humans, as they are "sit and wait" predators. This means they sit very still on a flower and wait for pollinators to visit, and then, quick as a flash, they'll attack and subdue their prey. Also of note, they can change color! Watch out chameleons, these eight-legged lovelies also have the ability to better blend in with their surroundings. Although it has to be said that they can't deviate greatly from their original color and the process takes a few days to complete.

The beautiful specimen we found on Sunday was a female. The sexes are very easy to distinguish as the males are a lot smaller and much less rotund. She was collected on the bright yellow, sunflower-like flowers of Encelia californica, commonly known as bush sunflower. Next time you are in the North Campus, check out the bush sunflowers planted atop the living wall. Who knew so much drama could be unfolding on each and every flower?

Crab spider versus European Honey Bee
(It was a tie, the honey bee flew away)

Thanks to Karen Ewald for taking the spider collecting picture.

Thursday, February 23, 2012

First Clouded Sulphur Butterfly Pupa in North Campus

Last week, Jany Alvarez, one of the Museum's Guest Relations staff, was sitting at the bus stop adjacent to the North Campus. While she was waiting for her bus, she saw an interesting sighta caterpillar crawling along the sidewalk! Thinking that the caterpillar would be better off on a plant than on the cement, she picked the caterpillar up and placed it carefully on a Dudleya plant on the Living Wall.

Later that day, another Guest Relations staffer watched the caterpillar pupate! By the time word travelled to me, the pupa looked like this:

Yellow pupa on Dudleya

When I came into work on Tuesday morning, the pupa had changed color! I took more pictures and went back to my office to identify it.

Close up of pupa. Note the small horn-like structure

The pupa belongs to a butterfly regularly seen in and around Los Angeles, the Cloudless Sulphur, Phoebis sennae. The Cloudless Sulphur belongs to the Pieridae butterfly family, which includes White, Sulphur, and Orange-tip butterflies. The most common butterfly in this family is the Cabbage White, which flies year round in our area and is a pest on vegetables such as cabbage, kale, and broccoli. In contrast the caterpillar of the Cloudless Sulphur feeds on cassia plants (genus Senna) and is often seen in our local deserts where the two California native species in this genus grow naturally. The altered nature of Los Angeles is such that non-native cassias are now common all over our area. They've been planted in various places like your neighbor's backyard, your local park, and even in the North Campus. The bus stop where Jany found the Cloudless Sulphur caterpillar is only 20 feet away from a few feathery cassias, Senna artemisioides, which were recently planted in the North Campus!

I guess our premise for developing habitat around the Museum is correctplant it and they will come!
Male Cloudless Sulphur from our Entomology Collection

Friday, February 17, 2012

American Goldfinches Find Feeders and Get Counted

American Goldfinches, Spinus tristis, have found our bird feeders! Flocks of them have been visiting the nyger seed feeders that the Museum's live animal caretakers fill on an almost daily basis.

American Goldfinch (upper left) and
Lesser Goldfinch (lower right) feeding on nyger seed

Like most finches, American Goldfinches are primarily seed eaters, making them some of the most readily-attracted birds to feeding stations. They are fond of the small seeds of grasses and annual plants, especially a type of thistle seed called nyger. Within 24 hours of putting up our first nyger feeders, we recorded both American Goldfinches and the very closely related Lesser Goldfinch, Spinus psaltria. Of the two species, Americans are slightly larger and more numerous, but are usually only present in Exposition Park from October to April. Thanks to Museum ornithologist, Kimball Garrett's hard work (uploading his regular Exposition Park bird lists), you can explore the seasonality of birds around the Museum. Check out the seasonal abundance charts in eBird; you'll find the goldfinches at the very bottom of the chart.

In the spring when American Goldfinches leave the park, they often head over to nearby streambottoms to nest. Some do travel a bit further afield, heading all the way to northern California or beyond. In contrast the Lesser Goldfinches can be found hanging around the park year-round. We haven't yet documented any nesting here, but now we have planted the North Campus, we hope to observe some soon.

In an effort to record the birds at our feeders and in the newly planted areas of the North Campus, this year we are participating in the Great Backyard Bird Count (GBBC). So this morning at 10 am Kimball tromped around the Museum's grounds and counted all the birds he could find. This is what he recorded:

1 Western Gull                 
1 Rock Pigeon
1 Mourning Dove
3 Yellow-chevroned Parakeet
4 Allen's Hummingbird (one female nest building)
1 Northern (Red-shafted) Flicker
2 Black Phoebe
3 American Crow
10 Bushtit
6 Yellow-rumped (Audubon's) Warbler
20 House Finch
13 American Goldfinch
15 House Sparrow

Kimball Garrett and Briana Burrows checking out the finches

Kimball Garrett is one diligent bird list maker!

Feeders and seed are generously donated to us by Wildbirds Unlimited in Torrance, CA

Friday, February 10, 2012

Blooming Agaves

More plant news from the North Campus. Recently some of our blue lotus agaves, Agave ceslii 'Nova', have begun to bloom. This is an impressive sight as these plants send forth long spikes, (between four and six feet long), that look a lot like giant asparagus stalks. This type of agave is monocarpic, meaning that it only flowers once, and this particular selection happens to flower at a relatively young age compared to other species. Incidentally, the genus is commonly called century plant because it can take decades for them to flower. The entire stand of this agave (approximately eight plants) is flowering at the same time, because they were all propagated from the same tissue culture, which is a common nursery practice for certain landscape plants. Although flowering signals the end of the plant's lifespan, we can expect to enjoy the flowers and fruits for the next several months!

Agaves reaching up to the floss silk tree

There are over 300 species of agave in the world, with 100 species native to North America. This large array of species includes well known agaves such as the tequila or blue agave, Agave tequilana, and the sisal or hemp agave, A. sisalana. Other species are also farmed to produce agave nectar, which is sweeter than sugar and honey.

The blue lotus agaves we have planted are native to Mexico and are becoming more common in the nursery trade. As with all agaves, the flower stalks possess literally hundreds if not thousands of individual blossoms, which are visited by many kinds of pollinators. The flowers will be a pale yellow color and will hopefully attract the numerous Anna's and Allen's hummingbirds that are already resident in Exposition Park. Unlike other agave species, the ones planted on the North Campus will not attract mammalian nocturnal pollinators, aka bats, which is a shame since we will be very soon putting up a bat box (more on that to come later)!
Four stately stalks!

Stop by the North Campus and check them out today! They are close to the Dueling Dinos on the North side of the Car Pak along Exposition Boulevard.

Thursday, February 2, 2012

First Baby Oaks Sprout Up in the North Campus

The North Campus is the proud parent of some baby oak trees!

Baby coast live oak sheltered by wall

Carol Bornstein, our new Director of the North Campus Gardens, discovered a couple of oak saplings on one of her recent outdoor forays. The babies are coast live oaks, Quercus agrifolia, of which we recently planted several trees. We've also planted another species of oak, the Engelmann oak, Quercus engelmanni (we planted only three of this species). Both species reside in the section of the garden called the urban wilderness which is composed of several kinds of California native trees and shrubs.

This might be the mother oak!

Oak trees provide amazing habitat value, and this is the main reason we planted them. By putting in such a  sizable stand of oaks we're hoping our created wilderness will provide habitat for a whole slough of organisms rarely, if ever, seen before in Exposition Park. In just one oak tree it would be easy to find hundreds of species of associated plants and animals and thousands of individuals (think how many birds, ants, or squirrels you find in an oak tree). One species that has already shown up with our oaks, is a tiny insect called a whitefly.

Crown whitefly nymphs on oak leaf
(each nymph is only 1 millimeter long)

It was once again thanks to Carol, who was out inspecting our lovely oaks, that we discovered these small insects. At first we thought they might be a scale insect, but Brian Brown, the Museum's Curator of Entomology, identified them as crown whiteflies, Aleuroplatus coronata. As adults these small white homopterous insects (group of insects consisting of aphids, cicadas, scales, etc) fly around to find a suitable location to lay their eggs. For the crown whiteflies their plant of choice is oak. What you see in the image above are the nymphs (immature forms) of the whitefly, they have no wings but are covered with white waxy secretions that make them look like little crowns. The nymphs feed on the leaf's juices by piercing and inserting their mouthparts into the leaf. They can cause damage to the plant's health if their numbers are high enough, and they can also transmit disease organisms from one tree to another (not unlike mosquitos transmit malaria).

Go check out your local oaks and see what animals live on them!