Monthly Archives: July 2014

TBT: How Cowbirds Know They Are Cowbirds

Bird Behavior, Songbirds

Immaure brown-headed cowbird (photo from Wikimedia Commons)

On Throw Back Thursday (TBT)…

At this time of year most birds have stopped breeding and are starting to flock for the coming winter.  Many of us have noticed grackle flocks and soon, I’m sure, we’ll see flocks of brown-headed cowbirds.

The fact that young cowbirds flock with each other is a miracle in itself.  Every one of them was dumped as an egg in another species’ nest where they out-competed their foster parents’ young.   Imprinting behavior says they ought to think they’re members of the foster species, but they don’t.

How do cowbirds know they are cowbirds?  Click here to find out in this Throw Back Thursday article.

 

(photo of an immature brown-headed cowbird by Cephas at Wikimedia Commons.  Click on the image to see the original)

 

 

Peppergrass

Plants & Fungi
Peppergrass (photo by Kate St. John)

30 July 2014

Here’s a pretty plant that grows in ugly places.

Peppergrass (Lepidium virginicum) is a native edible member of the mustard (Brassicaceae) family that occurs naturally in North and Central America.  Sometimes it’s cultivated for its peppery taste.  The young rosette leaves taste like mild arugula and the round flat seed pods, when chewed, are a substitute for black pepper.

However most of us know this plant — if we notice it at all — for its indomitable attitude toward degraded habitat.  It will grow almost anywhere, a trait that has given it the status of “Weed.”

I found this one growing from a crack in the sidewalk of the Greenfield Bridge.

Though one could eat the seed pods from a roadside specimen, don’t do it!   The soil next to a busy road is contaminated with toxic metals from car and truck exhaust. Plants in the Brassicaceae family are such good hyperaccumulators of metals that they can be used to clean up toxic top soil.  This roadside plant is full of toxins.

If you decide to taste peppergrass, look for a plant that’s in good clean soil far from the road.

(photo by Kate St. John)

Even Less Water Than We Thought

Climate Change, Musings & News, Water and Shore
Colorado River water loss as seen at Lake Mead, Nevada (photo from US Bureau of Reclamation)
Colorado River water loss as seen at Lake Mead, Nevada (photo from US Bureau of Reclamation)

29 July 2014

Rainfall in Pittsburgh is normal this year but out West they’re in their 14th year of drought with no end in sight.  This is starkly obvious at Lake Mead near Las Vegas where the water level has dropped 138 feet, leaving a “bathtub ring” of mineral deposits.

Seven western states and Mexico depend on Lake Mead for water; three states depend on its dam for electricity.  Since last October 4.2 million acre feet came into the lake but 7.9 million was withdrawn.  The lake has dropped 30 feet in the past five months alone.  As the water drops so does Hoover Dam’s generating capacity, putting the electric supply at risk too.

You’d think this problem could be fixed by controlling surface water consumption but it goes much deeper than that.

Back in January, I wrote about NASA’s GRACE satellite pair that measures groundwater from outer space (click here to read how it works).  Using nine years of GRACE data from the Colorado River Basin, University of California Irvine and NASA scientists made an alarming discovery.  From December 2004 to November 2013 the watershed lost 53 million acre-feet of water, an amount almost twice the size of Lake Mead.  More than 75% of that loss was from groundwater.  No one knows how much water is underground but it’s going fast.

When wells deplete groundwater, there are significant downstream consequences.  A 2012 study by Stanford Woods Institute found that overpumping can make the surface run dry.  Though surface water is carefully managed in the West, groundwater use is often poorly documented and barely managed — if at all.

Water loss at this scale affects every living thing.  Near Las Vegas the wetlands along Lake Mead are gone and so are the birds and animals that depended on them.

If the loss continues at this rate, humans may have to leave Las Vegas, too.

Read more about this study in Science Daily.

(photo of Lake Mead by U.S. Bureau of Reclamation)

S is for Snake

Insects
Eastern hognose snake (photo from Wikimedia Commons)

28 July 2014

If you’re afraid of snakes, please pretend this is a big “S” or close your eyes while you read.

I’m inspired to write about eastern hognose snakes today because summer is prime time for reptiles in Pennsylvania and a remark made in the PA Herps Facebook group has stuck with me since last winter: “The only way to get bitten by a hognose snake is to smell like its prey.”

The eastern hognose snake (Heterodon platirhinos) is native from Minnesota to southern New Hampshire, from Florida to eastern Texas.  It is more than two feet long and comes in so many colors and patterns that it defies an easy description.

I imagine that during summer’s heat I might see a hognose snake but the chance is slim.  I don’t look for snakes because I can’t identify most of them and some are poisonous.  My caution prevents discovery.

However, this snake is safe.  Very safe.  He won’t bite but he may scare you.  Wikipedia describes his defensive behavior:

When threatened, the neck is flattened and the head is raised off the ground, not unlike a cobra. [Cobra!!]  They also hiss and will strike, but they do not attempt to bite. The result can be likened to a high speed head-butt. If this threat display does not work to deter a would-be predator, a hognose snake will often roll onto its back and play dead, going so far as to emit a foul musk from its cloaca and let its tongue hang out of its mouth.

— description of eastern hognose snake, wikipedia

If I managed to get close to a calm hognose I’d see why he has this name — an upturned nose like a hog.

Ton an eastern hognose snake (photo from Wikimedia Commons)
Eastern hognose snake, closeup of head (photo from Wikimedia Commons)

But I’m not eager to get so close. If I scared him, the “cobra act” would frighten me. The “high speed head-butt” would certainly make me scream.  Both the snake and I would be lolling on the ground with our tongues hanging out.

S is for Sometimes Scary.

p.s. Despite the tone of this article, I am not afraid of snakes.

(photo of an eastern hognose snake from Wikimedia Commons, Creative Commons license.  I have horizontally flipped the original image to make an S. Click on the image to see the original at Wikimedia)

It’s Shorebird Time!

Water and Shore

American avocet, July 2014 (photo by Jessica Botzan)

After the summer solstice, shorebirds begin to migrate from their northern breeding grounds.

By early July the first wave reaches Lake Erie’s shore and our inland ponds and rivers.  This early group includes colorful adults still in breeding plumage.

Jessica Botzan photographed this gorgeous American avocet at Conneaut, Ohio last weekend.

It’s shorebird time!

 

(photo by Jessica Botzan)

Not Just A Pine Cone

Insects

Eastern fence lizard on a pine cone, 6 Jul 2014, VA Beach (photo by Kate St.John)

On Fourth of July weekend I was hiking at First Landing State Park in Virginia Beach when I noticed an odd-looking pine cone in the dappled shade next to the trail.  I paused to look more closely.

It’s not just a pine cone!

Here’s a better look.

Eastern fence lizard on a pine cone, 6 Jul 2014, VA Beach (photo by Kate St.John)

… and this view from a different angle.

Eastern fence lizard on a pine cone, 6 Jul 2014, VA Beach (photo by Kate St.John)

After two minutes of my ever-closer approach this lizard had had enough and ran away.

I know nothing about lizards so I googled images for a “brown lizard sandy shore Virginia” and found a photo whose description said “Matches the pine cone.”  How cool is that!  Someone else had photographed an eastern fence lizard on a pine cone.

I also found out that …

  • The eastern fence lizard (Sceloporus undulatus) is native to the eastern U.S. and southern Pennsylvania.  Theoretically I should have seen one in all my years of hiking near Pittsburgh but this is a first for me.  (I’ll admit I haven’t been looking very hard.)
  • Their scales are keeled, a feature you can see in the photos.
  • Eastern fence lizards are sexually dimorphic.  This one is female because her throat and flanks are whitish where adult males are shiny blue.  During the mating season males flash their blue bellies to attract the ladies and tell other guys, “This is my territory.” Click here to see the male’s amazing underside.
  • That flashy blue behavior is risky.  Flashy males are more likely to be eaten by birds.
  • In 2009 Penn State biologist Tracy Langkilde reported that eastern fence lizards who live where there are fire ants have longer legs than their predecessors 70 years ago — an example of evolution in action. They’ve also learned to twitch instead of freeze when they encounter the voracious ants that can kill them in less than a minute.

I’m glad I stopped to examine that pine cone.  I usually say, “Keep looking up” but it pays to look down sometimes, too.

 

(photos by Kate St. John)

Coming Soon?

Doves & Chickens

Eurasian collared-dove (photo by Chuck Tague)

PABIRDS was a-buzz this month about a non-native species that’s rapidly expanding across North America.  Though not yet established in Pennsylvania this bird has been seen in New York City.   Will it get here soon?

Originally native to India, the Eurasian collared-dove (Streptopelia decaocto) is non-migratory but habitually disperses northwest when its population expands.  It began its conquest of North America by human accident when a breeder released his flock of 50 birds in the mid 1970s after some escaped during a burglary in New Providence, Bahamas.  As the population expanded in the Bahamas the doves looked northwest and found … Florida!  180 miles of ocean was not a barrier.  Eurasian collared-doves were found nesting south of Miami in 1982.

By now the Eurasian collared-dove is resident from Florida to Seattle, from southwestern Canada to northeastern Mexico.  The Northeast is the only chunk of the continent they haven’t conquered yet.  Considering that they prefer urban and suburban settings with bird feeders and trees, it’s only a matter for time before they completely cover the U.S.

How do you recognize a Eurasian collared-dove?  They’re similar to mourning doves, pictured below, but bulkier with a black collar, a squared-off tail and, unlike escaped turtledoves, gray undertail vent feathers.  Here’s a photo of a Eurasian collared-dove in flight and here’s a mourning dove.  Notice the difference in tail shape.  The collared-dove’s three-coo song is different too.
Mourning dove (photo by Chuck Tague)

Some worry that Eurasian collared-doves will displace mourning doves but it doesn’t seem to be the case — at least in Florida where Cornell Lab’s Project Feederwatch studied both species in 2011.  Careful counts revealed that “Contrary to expectations researchers found that the abundance of native dove species was generally greater at sites with collared-doves than at sites without collared-doves.” Click here to read more.

What does the future hold for us?  Eurasian collared-doves are resident to the south and west.  They’re working their way up the coast and have made it to the Outer Banks of North Caorlina.  This month Vern Gauthier saw a pair in Lancaster County, PA.  They’ve been spotted in New York City.

Are they coming soon to Pittsburgh?  We should start watching!

 

(photos by Chuck Tague … who lives in Florida where Eurasian collared-doves are well established)

You Can See Her Egg!

Bird Anatomy

Gravid female northern cardinal, held for banding by Bob Mulvihill (photo by Kate St. John)

We learned a lot about bird anatomy, at the Neighborhood Nestwatch banding on Saturday.  Did you know that …

  • When you blow on the belly feathers of a songbird during the breeding season you see bare skin underneath.  This is the brood patch for incubating eggs and keeping nestlings warm.
  • Songbirds have translucent skin.  The red color is muscle under the skin, yellow is stored fat.
  • You can see the egg under the skin of a “pregnant” bird!

Even before he checked her belly, Bob Mulvihill could tell this female northern cardinal was gravid when he held her.   When he blew on her belly feathers we saw the white oval of the egg near her tail, circled below.

Gravid female northern cardinal, egg under skin (photo by Kate St. John)

This lady must have come out for breakfast before laying her egg and was delayed by the mist nets near the feeders.  She needed to get back to her nest soon(!) so Bob quickly banded, weighed and released her.  She immediately flew to the big maple and disappeared.

She weighed about 47 grams — 5+ grams heavier than normal because she was carrying the egg.  That’s a significant load to carry.

I hope she deposited it safely and that her morning turned out better than it began.  😮

 

(photos by Kate St. John)