Amphibian Egg Mass Surveys

One of the things I do in my spare time (for self-serving fun and career development as well as stewarding my planet) is volunteer with Northwest Trek and Washington Department of Fish and Wildlife conducting amphibian egg mass surveys. No, I don’t go door to door asking questions about egg masses. I go to a pond and look for the eggs that several species of amphibians left behind following breeding.

            First, what is an amphibian? It’s a critter that leads a double life as both a terrestrial and aquatic animal. Unlike a reptile like an alligator that must surface to breathe, amphibians can breathe above or below water. The word amphibian comes from the Latin amphi bios meaning two lives.

            There are 27 species of amphibians in Washington, but WDFW only has us looking for the eggs of 8. They are Oregon spotted frog (state endangered, federally threatened), red-legged frog, American bullfrog (invasive to the Northwest), Pacific tree frog, western toad (candidate for listing as federally threatened or endangered), Northwestern salamander, long-toed salamander, and rough skinned newt.

            The pond I survey is in Eatonville. In and around, I have found eggs, tadpoles, or adults of four of those species. There were Northwestern salamander, Pacific tree frog, and red-legged frog egg masses; adult Pacific tree frogs, a red-legged frog, and American bullfrogs; and some tadpoles that were too fast to be able to identify.

American bullfrog

Red-legged frog

Pacific tree frogs

            To conduct a survey, I go into the pond with my partner Roger and slowly walk around looking for eggs. It seems like a challenge at first, but the egg masses are very obvious in most cases. Northwestern salamander egg masses are a huge solid ball of jelly, about the size of a grapefruit. They are likely to be attached to a pond lily stem. Pacific tree frog masses are smaller balls of jelly attached to smaller aquatic plants in most cases.

Northwestern salamander egg mass

Pacific tree frog egg mass

            When we find egg masses, we mark the location on a GPS and take a picture. It also gets logged on a tracking sheet. Last March the batteries in either the GPS or camera died and the spare batteries in our pack were also dead. It was a little frustrating switching batteries from one device to the other, especially because that was the day a river otter was helping us. It would’ve been great to get a shot of that little guy! As a consolation, we found a pile of his poo.

River otter scat

            Gently cleaning our waders before and after conducting a survey is a thoughtful way to help prevent the spread of invasives from one pond to another. It can also help reduce the spread of chytrid fungus, which causes disease in amphibians.

            The data we collect gets sent to the state to help biologists determine habitat conditions and species trends. Amphibians are an indicator species (species that can indicate trouble in an ecosystem by absence or presence) because their thin skin makes them very sensitive to environmental changes. By identifying trouble early on, biologists can analyze and correct the situation.

            Now you have a glimpse inside the working world of a nature guy. I’ll be back in the pond for a third season of egg mass surveying, starting this week. Weather permitting, of course. Don't forget to like Nature Minute on Facebook!

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Animal Attraction

In a previous episode of Nature Minute we talked about porcupine love. With Valentine’s Day right around the corner it’s time to revisit the subject.

In the human world, success is usually measured in money and power. In the natural world, success is measured by passing on genes to a new generation. Darwin proposed evolution as natural selection by survival of the fittest. Those best equipped to survive their environment will have the most offspring, in theory.

There are two ways in nature to ensure that your offspring will survive to produce offspring of their, furthering your own genes. The first is a high reproductive rate (fecundity) with little to no parental care. The second is lower fecundity with a high rate of parental care.

Some examples of high fecundity animals are insects, which lay thousands of eggs, and mice, which may have multiple litters of a dozen or more in a single year. Surviving mouselings reach sexual maturity at a very early age and have babies that are older than their aunts and uncles. Many plants fall into this category also. Think of how many wishes you’ve made with dandelion seeds. Or if you are like me, think of how many mornings you woke up to a yard full of dandelions that weren’t there the night before.

Lower fecundity breeders are typically larger than high fecundity breeders (this is a general rule, but there are exceptions of course). We fall into this category, along with whales and elephants. We all have a relatively long gestation period (40 weeks for people, 20 months for elephants) and births are commonly single. Sexual maturity takes years to reach and mothers do an excellent job of caring for their young.

Just as there are two ways of breeding, there are also two ways of breeding- monogamy and promiscuity. Monogamy is what we think of in human relationships, a pair mating for life. Bald eagles and barn owls are monogamous.

Promiscuity can be either male or female. Male promiscuity is very common in the natural world (and humans too). A successful male has many offspring, but why should he limit himself to a single female? In these situations, frequently a dominant male will have a harem of females to mate with. Elk and bison are great examples. Going back to a previous Nature Minute on the elk rut, we learned that young males will challenge the older dominant male for the right to mate.

Elk rut, photo by Tom Bartel

Female promiscuity is way to confuse males. In some species, a male will kill any young that are not his own. He wants his own genes, and not someone else’s, to be passed on in perpetuity. To counter infanticide, in some species the female will take multiple mates. Since no one is really sure who the father is, all males assume fatherhood and are unlikely to kill any young since it very well could be their own. It is even possible for all of them to be the father. Bees, hedge sparrows, and garter snake females will all take multiple mates.

In the human world, typically a boy will ask a girl out on a date. Females hold all the power. The same is true in the animal world in many cases. Males will put on a courtship display or perform a courtship ritual, hoping to catch the attention of a lucky lady. Prairie chickens have a lek, which is similar to a middle school dance, but the stakes are higher. Boys on one side, girls on the other. The males strut their stuff and the females pick out their favorites. After it’s over, they all go back to their home territories. Usually there is some desirable trait that females are looking for that demonstrates the male’s fitness (as is “survival of the fittest”, not like a fitness test in gym class). It can be brightly colored feathers, awesome dance moves, the loudest croaking, huge antlers, or any number of other things. The male with the best traits gets to pass those on to the next generation through his genes.

Greater prairie chicken lek, photo by Adrian Binns

So what did we learn today? When it comes to love, people are still pretty much animals. It’s ladies’ choice, and the guys really don’t care as long as she says yes.

Species of the Month: Groundhog

February’s Species of the Month is another little critter we associate with winter weather. Or spring. It’s everyone’s favorite amateur weather prognosticator, the groundhog. No matter what his prediction is, it is still six weeks until spring and six weeks of winter. Information and picture this month come from University of Michigan’s Animal Diversity Web.

Scientific name: Marmota monax

Kingdom: Animalia (animals)

Class: Mammalia (mammals)

Order: Rodentia (rodents)

Range: Eastern US from the South to eastern Canada, west across Canada as far north as southern Alaska

Habitat: Grassland, forest, urban and agricultural areas.

Lifespan: 4-6 years

Diet: leaves, bark, seeds, grain, flowers, insects, eggs, mollusks

Predators: wolves, coyotes, foxes, bears, lynx, bobcats, hawks, snakes, domestic dogs

Conservation Status: No special protection

Other Information: Also known as the woodchuck and whistle pig. If it could chuck wood, it chucks unknown amounts. Abandoned dens find new life hosting a diverse array of critters including foxes, ground squirrels, skunks, and raccoons. Ecosystem functions groundhogs perform are seed distribution and soil aeration. They are able to climb trees and make a whistling call when frightened. Other sounds are hissing, growling, and teeth chattering. A hibernator, they sometimes wake up early, giving rise to the Groundhog Day legend. Favorite plant foods include clover and dandelion. Groundhogs are used for biomedical research and are a crop pest.