Video
Science Behind the Scenery: Myrtle's Silverspot Butterfly
Transcript
[birds calling and singing and insects buzzing]
[Dawn Adams] We are here at Point Reyes National Seashore in Northern California, about an hour and a half north of San Francisco.
[birds singing and insect buzzing]
This area was set aside in 1962, in part, to preserve the diminishing coastline of California.
[birds singing in the distance]
One of the species is the Myrtle's silverspot butterfly. Orange and black, it's a fairly large butterfly, but smaller than a monarch. And, on the underside of its hind wings, it has silver spots.
[birds singing and insect buzzing]
In 1998, we weren't sure of its existence. Only 20 individuals have been counted in this area that we're in now.
[birds singing in the distance]
Myrtle's silverspot butterfly was listed in 1992 as endangered. In order to determine something is endangered, studies are done looking at the...the full habitat or area of the range that an animal is found. And if it seems that the...the numbers are so low that it could go extinct in a short number of years, then it's listed as endangered
[birds singing and insect buzzing]
A threatened species is one that is moving toward this endangered listing.
[silence]
[Geoff Smick] This butterfly would be a good indicator of the health of the ecosystem, in general. And if the butterfly's populations are failing, then that means that something's going wrong out here, and we need to try and figure out what that is and make a remedy, if that's possible. And, so, if it's doing well, then, probably, chances are the rest of the ecosystem is doing pretty good, too.
[birds singing and insect buzzing]
[Dawn Adams] There's two population centers that we've been working with. One in this area, in North Beach, that goes from about Abbotts Lagoon south to Drake's Beach. And they'll use the dunes primarily, but then also the grasslands, for laying eggs.
[birds singing and insect buzzing]
In Tomales Point area, at the very far north of the peninsula, there's another population that seems to use a different group of nectar sources because there's no coastal dunes up in that area. And also lay eggs in that same area.
[birds singing]
With this species, the larvae are very hard to find. They tend to hide, they often feed during the night or early morning, late evening. So, in this case we're...we're studying the adult butterflies in order to get population counts.
[birds singing]
Female butterflies lay eggs in late summer, early fall and the eggs hatch a couple weeks later. And they exist as very very small, couple-millimeter-long caterpillars throughout the winter. And in the spring, they wake up and they go through more growth cycles, about six growth cycles, where they become bigger and bigger larvae.
[birds singing in the distance]
The adult flight season lasts from about mid-June to early September. So, during that period of time, they're flying around looking for nectar sources.
[birds singing and insect buzzing]
Females will be looking for violets to lay eggs. The violets are important to the butterfly because it's the larval host plant.
[birds singing]
The violet is the only plant that the larvae can feed off of.
[birds singing and insect buzzing]
[Geoff Smick] This specific butterfly, the Myrtle's silverspot, uses just Viola adunca, the Western dog violet. The butterflies have very sensitive chemosensory organs, mainly in their antennae, and they can actually smell the plants—the plants give off some chemical odor. They fly up nearby, see if it's a suitable plant, and then they'll lay their eggs nearby the plant.
[insect buzzing and birds singing in the distance]
So, there's, uh, about four different aspects of our research that we're doing. One are the violet surveys. Another is the actual counts of the butterflies. Additionally, we can get some information on the types of plants that the butterflies are using. We frequently see them nectaring on flowers when we're out doing our surveys. Another aspect of our research that we do are surveys of these actual nectar plants. We go into the dunes, specifically, 'cause that's what we consider the prime habitat and the most threatened. And we go through with a tape measure and do 50-meter transects and look along those...along the tape measure and try and count how many nectar plants are there.
[birds singing and insect buzzing]
[Dawn Adams] One of the main reasons, um, and, goals behind this two-year intensive study of the Myrtle's silverspot butterfly is so we can track the butterfly's population and the nectar sources it relies on to develop a management plan. When there's a problem, we have some tactic we can take to improve the habitat for the butterfly and increase its numbers.
[birds singing and insect buzzing]
Description
The sixth part of the ten-part Science Behind the Scenery documentary featuring biologist Dawn Adams and Geoff Smick talking about the endangered Myrtle's silverspot butterfly and efforts to protect it and its habitat at Point Reyes National Seashore.
Duration
5 minutes, 27 seconds
Credit
Pacific Coast Science and Learning Center
Date Created
03/24/2004
Copyright and Usage Info
Tags
- point reyes national seashore
- point reyes
- pacific coast science and learning center
- pcslc
- science and learning center
- science and learning centers
- science behind the scenery
- science
- myrtle's silverspot butterfly
- silverspot butterfly
- butterfly
- butterflies
- speyeria zerene myrtleae
- speyeria zerene
- nymphalidae
- lepidoptera
- insect
- insects