Tag Archives: mating

Trouble in love town for the faithful Sierra Nevada yellow-legged frog

Sierra Nevada yellow-legged frog. (Photo/Devin Edmonds)

Sierra Nevada yellow-legged frog. (Photo/Devin Edmonds, http://www.amphibiancare.com)

Most people consider loyalty an admirable trait, but for the Sierra Nevada yellow-legged frog, faithfulness to a compromised breeding ground just might spell doom for the species. In many places, the frog’s habitat is drying up or swarming with ravenous introduced trout. A new study released by the USDA Forest Service in the Canadian Journal of Fisheries and Aquatic Sciences details the extent of this troubled relationship, and provides insights key to giving the frog a chance at survival.

Mountain yellow-legged frogs, (of which there are two species), adapted to live in high alpine lakes, in environmental extremes too cold and harsh for most amphibian species. This specialty helped the frogs thrive, but in the past century, the once common Sierra Nevada yellow-legged frog has disappeared from more than 90 percent of its range. In 2003, the U.S. Fish and Wildlife Service ruled that the mountain yellow-legged frog “warranted” endangered species listing, but was precluded due to the need to list more high priority species.

Likely culprits for the frog’s decline include the usual suspects like disease and contamination, but new research shows that the periodic drying up of habitat and predation from introduced trout coupled with the frog’s loyalty to specific breeding spots is pushing the animal ever closer to extinction.

Yellow-legged frogs need up to four years for their tadpoles to mature. So if a pond dries up, the species could lose up to four year-classes of offspring, issuing a serious blow to that particular population. The study also found that for some of the best ponds left for the frog, introduced trout then threaten the species. Offer a trout a yellow-legged frog and it won’t turn you down, no matter what the life stage of the dangling amphibian.

Kathleen Matthews and Haiganoush Preisler, scientists with the USDA Forest Service’s Pacific Southwest Research Center, conducted a 10-year study to measure the fidelity of yellow-legged frogs in Kings Canyon National Park, east of Fresno, Cali. They used mark-recapture techniques, and observed frog tendency to return to lakes even for locations that tended to dry up in low snowpack years, or where frogs had previously encountered predatory fish.

Fish removal appears to be a strong restoration technique, and projects underway show a rebounding in the order of tens of thousands of frog and tadpole populations in lakes where non-native fish have been eradicated. There may just be a little bit of hope yet for the garrulous hoppers, especially if restoration efforts incorporate knowledge of site fidelity into their tactics.

You can learn more about the natural history and restoration efforts behind this little frog at MYLfrog, or download the USDA Forest Service study here.


The high fidelity of alligator love

Two American Alligators (Photo/Matthew Field)

Two American Alligators (Photo/Matthew Field)

Oh alligator love, it’s not as fickle as you might think. Get on a gator’s good side and you may just have found a friend for life, if you’re another alligator of course.

In a study that combines field science with molecular biology, researchers from the Savannah River Ecology Laboratory found that alligators were surprisingly loyal partners and akin to birds in their mating habits. The discovery offers new insights into evolutionary links and behavior of crocodilians, birds and dinosaurs – and certainly, at least where one science writer is concerned, proving there is a lot more going on behind those alligator eyes than a cold reptilian stare.

Researchers trapped and re-trapped alligators at Louisiana’s Rockefeller Wildlife Refuge, 76,000 acres of alligator dream real estate bordering the Gulf of Mexico. “Given how incredibly open and dense the alligator population is at RWR, we didn’t expect to find fidelity,” said researcher Stacey Lance. “I don’t think any of us expected that the same pair of alligators that bred together in 1997 would still be breeding together in 2005 and may still be producing nests together to this day.”

Crocodilians have already proven to be more invested in the care of their offspring than most other reptiles, actively nurturing young and defending nests. Crocodiles are even known as considerate egg-layers. As a female drops the egg, she will blindly catch it with a hind leg before it hits the ground and gently place it in the nest. But up until now alligators were thought to be polygamous, mating with several different partners and leading to many fathers for a single nest.

After ten years of following alligators at the refuge, scientists Lance, Travis Glenn, Ruth Elsey and Tracey Tuberville discovered that 70 percent of female alligators stick with who they like. Even if they have multiple partners, the same bachelors get picked year after year, regardless of whether females encounter a new slew of potential suitors.

The study marks the first time fidelity has been observed in any crocodilian species. “In this study, by combining molecular techniques with field studies, we were able to figure something out about a species that we never would have known otherwise,” said Lance. “Hopefully future studies will also lead to some unexpected and equally fascinating results.”

Results of the study were published in the October 7 issue of Molecular Ecology.

Lady bug swarm turns Green Mountain red

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Lady bugs unite! When a friend of mine posted some photos she took while on a hike on Boulder’s Green Mountain, I couldn’t believe my eyes. I saw entire tree trunks covered in red. The red was lady bugs, a mass gathering of a gardener’s best friend, as they search for mates and prepare to hibernate for the winter. Now this was something I had to see for myself.

Of course, not everyone can make the hike to Green Mountain, but hopefully you can live a little vicariously through this slide show, and learn a little something new about this “cuter” member of bug-dom.

There are more than 400 species of lady bugs, (or as they’re more officially known ladybird beetles), in North America. This year has been an unusual one for lots of natural phenomena in Colorado — a wet, cool summer has led to an endless green summer and multitudes of wildflowers — and this year’s lady bug gathering is no exception. Boulder Open Space and Mountain Parks estimates that this could be a record-setting year for the annual swarm.

Besides the slideshow, I’ve made a little list of interesting lady bug facts you might not know.

  • They’re cannibals.
    • at least during their larval stage. Researchers recently discovered lady bug babies hatch and eat their siblings. Don’t get too disillusioned. They grow out of it.
  • They don’t change their spots.
    • Some people think you can tell the beetle’s age by the number of its spots, but according to the Boulder Open Space and Mountain Parks, you keep what you’re born with when it comes to the dots.
  • They “play dead.”
    • If an adult ladybug feels threatened it will fall down and “die,” or let off a foul yellow ooze from its leg joints that most animals won’t want to eat, (University of Arizona)

Monarch flycatchers: Catching the moment one bird species becomes two

Plumage variations of the monarch flycatcher. (Photo/Courtesy J. Albert Uy)

Plumage variations of the monarch flycatcher. (Photo/Courtesy J. Albert Uy)

How do you measure the instant one species becomes two? Well, in the Solomon Islands, biologist J. Albert Uy is trying to pick a fight with monarch flycatchers to find the answer. The fight’s tipping point has to do with a bunch of feathers, a change in plumage colors that is allowing scientists to capture a snapshot of evolution in action.

A territorial flycatcher (Monarcha castaneiventris castaneiventris) aggressively responding to a taxidermy mount during our mount presentation experiment. We used mount presentation and song playback experiments to test if divergent plumage color and song are used in species recognition between sister taxa (described in Uy et al. 2009). (Photo/Courtesy J. Albert Uy)

A territorial flycatcher (Monarcha castaneiventris castaneiventris) aggressively responding to a taxidermy mount during our mount presentation experiment. (Photo/Courtesy J. Albert Uy)

Flycatcher males are territorial and will launch an avian smackdown towards perceived rivals trespassing on their turf. But a flip of a single gene is turning the monarch flycatcher into a bird of a different color, and in the process changing the social dynamics of rival birds.

It seems that though they are technically still the same species, the black-feathered flycatcher didn’t get the memo about their chestnut-bellied kin, and vice versa. Uy tested this by invading flycatcher territory with dummy birds. What he’s found is that the two don’t see each other as rivals, and are therefore probably more interested in mating with their like-feathered counterparts.

At least in the case of the monarch flycatcher, this single gene and spot of color heralds the birth of an entire new species.

J. Albert Uy (Photo/ C. Low, courtesy J. Albert Uy)

J. Albert Uy (Photo/ C. Low, courtesy J. Albert Uy)

We often hear about species being lost, but rarely do we learn of one being created. Uy’s work provides a glimpse of the “fork in the evolutionary road” as it happens in real-time, and what that could mean for our understanding of bird life.

Uy’s work appears in the current edition of American Naturalist, and you can read more about monarch flycatchers in the 2005 New York Times article, “In Give and Take of Evolution, a Surprising Contribution from Islands.”

Bait fisheries drive decline of bird species

(Photo/Andrew Easton, 2004)

(Photo/Andrew Easton, 2004)

Every year the horseshoe crabs gather to spawn, releasing thousands of eggs along the Delaware Bay coast. And with timing perfected by evolution, red knots, a bird enduring one of the most impressive yearly migrations from the Arctic to the Tierra del Fuego, arrive just in time to gorge on the eggs of the horseshoe crab. It is a vital stop on the “peeps'” spring migration. But the crabs and their eggs are disappearing, a loss with dire consequences for the little birds.

Red knot populations have fallen more than 75 percent in recent years, and new research published in this month’s issue of Bioscience reveals that Red knots can thank the bait fisheries for their hungry stomachs. Within half a decade the fisheries harvesting horseshoe crabs grew 20-fold, gobbling up more than 2 million crabs a year and effectively eliminating 90 percent of the eggs that red knots rely upon to survive their almost 19,000 mile migration.

But this research is not just a blame game for the fisheries. A coalition of scientists worked together on this study to help draft recommendations for the adaptive management of the bait fisheries that could help all three groups survive.

Woe betide the lovesick lamprey

Love is in the water, and the lamprey swears she’s found her match. She swims the corner ready to score. That’s when they spring the trap. 

Scientists out of Michigan State University are using chemical trickery to seduce and capture female sea lampreys, a devastatingly invasive species found in the Great Lakes. A single lamprey can eat up to 40 pounds of fish, and they’re to blame for the extinction of at least three whitefish species.  The voracious predators have proven difficult and expensive to control, costing the U.S. and Canadian governments $10 to $15 million a year.

But males it turns out, release an irresistible chemical into the water attracting females from more than a hundred meters away, and this mojo might just be the key to the lamprey’s undoing.  Weiming Li, a professor of fisheries and wildlife at MSU, and his team spent years isolating and synthesizing a fake version of sea lamprey love potion. Now they’ve landed on a treatment that is as effective as the lamprey’s own and when used in small doses could effectively treat sea lamprey infested waters. 

“The commission considers regulating spawning and migrating behavior with pheromones the most promising control method for implementation,” Li said in a press release. “So we’re excited about the possibilities.”

You can learn more about this promising new treatment method in the latest version of the Proceedings of the National Academy of Sciences.

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