Sunday, July 12, 2020

Tiny Body, Big Voice--And Oh, Those Legs!

If you thought these little guys were loud in the spring, you should hear them now!   Here are Blanchard's Cricket Frogs on the shores of McDowell Creek:

They make a lot of racket for frogs that are no bigger than a quarter:   

Blanchard's Cricket Frog on Algae-covered Rock by McDowell Creek
Their vocalizations are part of what's called a "breeding chorus."

But there is a lot of mystery surrounding breeding choruses.  For one thing, they can occur separate from breeding.   

Sometimes the males just gather and sing, no females allowed.   And the male Blanchard's Cricket Frogs do a "leg display."

But what's the purpose of these all-male displays?  Famed herpetologist Joe Collins wrote that sometimes the frogs gather "for unknown reasons."  So we can observe and speculate.  The little guys don't appear to be defending territories or establishing dominance.   In fact, their interactions are more congenial than aggressive.  They even appear to take turns sitting on top of each other and showing off those gorgeous hind legs.  

If you have any ideas about what the adaptive advantage could be that impelled the evolution of leg-displays, share it with!

"Breeding" takes place outside the frogs' bodies.   Females deposit eggs underwater, and the males then fertilize the eggs externally.  
All photos and videos were taken at Bird Runner Wildlife Refuge, an AOK Legacy Sanctuary in Geary County.  Photos, videos and text by Margy Stewart.   

Wednesday, July 8, 2020

Summer Damselflies

Summer is the time for procreation!   Here "dancer" damselflies (Argia spp.) are laying eggs in McDowell Creek.   The pairs have mated, and now the females are placing eggs in underwater vegetation or other substrate.   The males are "mate-guarding"--hanging onto the females and keeping other males at bay.

That clicking noise you're hearing is the breeding chorus of Blanchard's Cricket Frogs--also abundant near McDowell Creek.

The males have little grabbers on the end of their abdomens which fit exactly into slots behind the females' heads.  The exact fit means they can hang onto the females of their own species but no other.  

Here the males appear to be pushing the egg-laying females down into the water.  But don't worry--the females grab a bubble of air and keep breathing, even under water.     

Soon the eggs will hatch into aquatic larvae, called "nymphs."  Both the adults and the nymphs are great predators, feeding on mosquitoes and other insects in the air and in the water.   

Damselflies hate pollution, so their presence indicates a healthy stream.   These Dancers love streams with limestone bottoms, such as McDowell Creek.

Damselflies don't go through a complete metamorphosis--there is no pupal stage.  Instead, the aquatic nymph molts and grows and finally climbs out of the water to molt one final time.  The exoskeleton splits open and out comes a gorgeous damselfly, a beautiful adult with wings!

Damselflies are in the same family with dragonflies but they are smaller and thinner, and when perched they hold their wings upright, whereas dragonflies spread out their wings. 

Damselfly holding wings upright.  See how thin he is
compared to a dragonfly?

Dragonfly holding wings outspread.  See how hefty he is
compared to a damselfly?