Thursday, May 29, 2014

The Remarkable Oriole Nest‏

Male Baltimore oriole attending nest
Female Baltimore oriole building nest
Baltimore oriole nest in red maple at farm in VA

One of the most beautiful birds in North America, which migrates to the neotropics in winter, is the Baltimore oriole.  The bright orange and black colors of the male, its habit of living around houses and farms, plus a very loud and melodious song make it very conspicuous.  We enjoy seeing orioles in Florida as they migrate north and we arrive at our VA Blue Ridge farm about the same time as the orioles in late April.  The hanging pouched nest of the Baltimore oriole is quite unusual.  We are fortunate to have a pair living in a large red maple in our front yard and can observe all of the interesting breeding activities.  After the male and female have settled in after migration, they are seen searching together for an appropriate nest site.  They favor the ends of long pendulous branches and are likely trying to avoid the depredations of predators such as the fox squirrel and black rat snake which are common in the area.  Have a look at the general nest area and see if you can spot the nest hanging on the left side of the maple over our drive way. For such a distinctive structure it can be hard to find.

The female begins the nest by looping grass fibers around twigs and gradually building up a cup.  Then she goes inside the cup and appears to tie the ends of fibers into one another to knot them together.  In a remarkably rapid fashion she completes the complex nest, in this case between May 5 and 12.   

The degree to which these orioles tolerate and even seek out human-modified landscapes is interesting.  They appear to have benefited from the clearing of the original forests.  They are also attracted to riparian or riverine habitats.  They vigorously defend their breeding territory.  When one of their blackbird or Icterid cousins, such as a redwing, ventures near their nest they immediately chase away the intruder.    

The origin of such peculiar and distinctive nests is a subject of some interest.  It would appear to be a direct result of predation pressures from tree-climbing snakes and mammals.  The mere ability to build such an amazing structure is awesome and presumably instinctive.  The ultimate expression of the habit of building hanging nests is found among other icterids, the oropendolas of South and Central America, which build very long, hanging nests in colonies.  It is easy to see how the orioles could represent an earlier stage in the evolution of highly visible, hanging nests.  It is especially remarkable how the change from the usual condition in birds, highly secretive nest building, progresses to completely visible nests in colonies, which are so difficult to access that most predators are stymied.   

Bill Dunson 
Female Baltimore oriole building nest

Baltimore oriole nest in red maple on VA farm

Fox squirrel

Black rat snake

Tuesday, May 27, 2014

Peter and David at the farm

Grandson Peter and son David spent the Memorial Day weekend with us at our VA Blue Ridge farm and enjoyed running/biking on the New River Trail and swimming/tubing in the pond.  They are camping out at the cabin one night before heading back to the big city (Chapel Hill, NC).

Cheers-
Grandpa Bill





Friday, May 23, 2014

The Joys of Butterfly Watching‏


I always advocate going into nature with an open mind to observe everything of interest.  A small point and shoot optical zoom (40-60 x) camera is of great assistance in identifying your finds since you will need to examine the details later in comparison with reference books or websites.  I have found this particularly important in trying to learn the butterflies which can be complicated.  Yet there is nothing in nature more beautiful than a butterfly.  But the excitement of finding a new or unusual butterfly is enhanced if you are able to identify it and share the find with others via your photos.

Little wood satyr
If you focus on learning the most common ten species in your area you will find it much easier and less frustrating to make progress.  Many species are widespread so you can also practice while you are traveling.  We spend most of our year in FL and VA, but were recently visiting my son's family in Chapel Hill, NC.  On a single short morning walk (after 10 am is best when it is warmer) along a wooded path with some flowers in bloom we found some species I knew and some I did not recognize.

Red spotted purple
The red spotted purple is one of the confusing "black and blue" butterflies that apparently mimics the toxic pipevine swallowtail.  But it is not a swallowtail but a brushfoot butterfly and lacks the tails.  The bright coloration and its habit of spreading its wings along sunny pathways are characteristic.  It occurs from middle FL all the way to Canada where it interbreeds with the white admiral.

Silvery checkerspot
The silvery checkerspot is widespread in the east but is only found in FL in the western panhandle.  It strongly resembles the pearl crescent which is smaller and common from FL north.  The question  mark in its orange form is quite beautiful and confusing to separate from the comma unless you take a photo so that you can count the black spots and examine the wing shape.  

Carolina satyr
The satyr butterflies comprise a group which can also be confusing.  They fly when it is fairly cool so you may often see them from FL northwards.  The spot patterns on the outside and inside of the wings are the key to identification.  Note that the Carolina satyr has only one eye spot on the fore-wing whereas the little wood satyr has two.  The Carolina has no eye spots on the inner surfaces of the wings in contrast with the little wood which has eight eye spots.  A cryptic species of the Carolina has been discovered in TX (the intricate satyr) which looks the same but has different genitalia and genetic makeup.  Since the eye spots are believed to fool predators into thinking that the helpless butterfly is a scary snake or owl, variation in the numbers and placement of the spots is interesting.

Zebulon skipper, male
Certainly the most confusing of all butterflies are the skippers which have few distinguishing marks that are obvious without prolonged study.  There were several zabulon skipper males sunning along the path and a photograph enabled me to get expert opinion to identify them.  

Finally one of the most beautiful insects along the path was not a butterfly but a beetle.  A common and very easily recognized tiger beetle (due to its bright green color) is the six spotted tiger beetle.  They run along the ground and sun themselves to raise their body temperature, and make short flights which searching for prey.  They resemble a tiny tiger in their predaceous feeding behavior.
Six spotted tiger beetle

So I encourage you to broaden your natural history horizons to include any and all objects of interest.  A walk in virtually any habitat will yield numerous critters and plants that will brighten your day and challenge your identification skills.  

Bill Dunson

Wednesday, May 21, 2014

Sea turtle freak?



This is a cute article about turtle geeks/freaks in the Emory University magazine that I thought you might enjoy.  It helps to explain why so many people devote their time and passion to helping sea turtles and other chelonian species.  

Cheers- Bill 


Thursday, May 15, 2014

The high value of sweat for butterflies

After a sweaty morning working in the woods I sat down on the porch to catch a few breezes.  I took my soaking wet shirt off and hung it up to dry on the steps.  To my amazement, almost immediately a silver-spotted skipper butterfly lighted on the damp shirt and began to drink the sweat!  What is going on here?

Butterflies are well known to require sodium salts which are lacking in their vegetable diet and they seek salts in animal feces and damp soil which have minerals.  I noticed this same butterfly landing on white spots which might have been bird droppings.  But how did it know that my shirt contained sodium from my sweat?  Surely it does not recognize a shirt as a source of sodium, but it may well be able to smell and identify a sweaty mammal, which is likely to have excess sodium available to drink?

So if you want to attract butterflies, save up those sweaty shirts and hang them out as a lure.  You could even add salty water to a particularly sweaty and smelly undergarment to act as a lure.  You can add these to the rotten fruit and other strange objects that people use to attract butterflies to their backyards.  You may attract fewer neighbors but more butterflies!  By the way this would make a great science project for kids, testing various smells and salts as attractants for butterflies.

Bill Dunson

Tuesday, May 13, 2014

Life on the Edge


While walking along the banks of Crooked Creek several miles from our VA Blue Ridge farm I came across this crooked beech tree precariously perched on the edge.  Kind of reminds me of my life at present?!  When the form at the doctor's office asks how your general health is, this photo might summarize it pretty well.  Well, so far so good.  But the next flood could be a problem!

I thought I would send it to you philosophic/artistic types in case you might want to consider it as a subject of reflection.

All is well here down on the farm although work is always piling up.  The wildflowers have been fantastic this year and the birds pretty good too.   

Cheers- Bill

Tuesday, May 6, 2014

A new duck in town‏

Black-bellied whistling duck
Hey Bill, 
On my way to the beach this a.m. (7:30), spotted a flock of 10 ducks perched on the roof of 2 story house. They had a red bill, white area under beak, white wing bar, primarily chestnut with black underbelly. The sound they made when taking flight it what mostly grabbed my attention. It was a squeal, rather than a quack. Like nothing I'd ever heard before. Came home and found it on the internet, with recorded sound. BLACK-BELLIED WHISTLING DUCK. They apparently are expanding their range. So exciting! 
Keep your wonderful articles coming; I love it! 

Pat Gordon 
Don Pedro Island 

A Late Spring Nature Ramble in the Blue Ridge‏

Fire pink
We arrived back at our VA Blue Ridge Mountain farm a bit later this year in early May.  I thought that spring might be mostly over, but I should not have worried since there was a virtual explosion of bird singing/breeding and wildflowers in bloom.  However the insects (butterflies and dragonflies) were far from their peaks of activity.  

To get an idea of the diversity of flowers just consider three flowers that I came across yesterday.  Fire pink is an astonishingly beautiful and common flower in this area that blooms for a very long period.  The long corolla tube and bright red color are designed to attract hummingbirds which are recently migrated from Central and South America; the name fire pink refers to the "Pink" family of which it is a member. 
 
Bleeding Hearts
The bleeding heart is a bizarre looking flower whose shape seems to defy reason; it is primarily pollinated by bees.  The showy orchis also is a very atypically shaped orchid flower, which is designed to attract bumblebees as pollinators; the bluish color is very attractive to bees and there is a landing pad from which the bee can insert its tongue into a spur containing nectar.  In the process two pollinia are glued to its head. The process is nicely illustrated at the website AbundantNature.com.

Showy orchis
This time of year is primarily a flower and bird show, but there are some butterflies out and about.  One of the most difficult to identify is the azure which occurs in a variety of species that are virtually impossible for the amateur to identify.  The scientific name for such closely related forms is "sibling species," and they provide compelling evidence for the inexorable march of evolution in the  present time.  The co-occurrence of very similar but genetically different "species" illustrates how forms are diverging from one another and becoming distinct species.   
 
Azure butterfly
The almost overwhelming amount of bird song in spring is very impressive and thrilling.  I enjoy identifying birds by their songs, so it is a challenge to separate the many species when they are singing all at once.  I especially enjoy seeing and hearing birds that have recently passed through our Florida yard.  
Indigo bunting, male
Two examples are the orchard oriole and indigo bunting, whose males are beautifully colored to woo their females.  The indigo male loses its brilliant blue color during winter; this is not surprising since bright blue must be easy for predatory birds to spot. Of course the purpose of all this song and color in male birds is to breed.  I found an enchanting phoebe nest in the same location as usual under my cabin, built of moss, and filled with six white eggs.  
Orchard oriole, male
The white eggs would seem to be easily visible to predators since they are not camouflaged, but the nest is typically located up under some cover and the eggs are not easily visible.

Spring is such a wonderful time of year that "heaven on earth" for the naturalist might be considered a place of perpetual springtime.  Of course I find natural wonder and beauty at all times of the year and in all habitats, but May is certainly one of the easiest months in which to find enjoyment in nature.

Phoebe nest with six eggs under cabin
Bill Dunson 

Saturday, May 3, 2014

Monk skipper on orchid‏


One of the seasonal orchids that is always in bloom during the Easter season and for many weeks before and afterwards is the crucifix orchid, so named for the shape of the flower.  It is a spectacular flower that is quite easy to grow and is a feast for the eyes.  It does not often in my experience attract hummingbirds or insects, but recently I found this monk skipper on the flower in my FL backyard, possibly resting after a drink of nectar.  The coincidence in space of a grass skipper named for a priest and a flower named for the crucifix is interesting.  

Bill Dunson

Lizard's Eyes Bigger than Mouth?‏



This FL brown anole seems to have an appetite bigger than its mouth.  It has captured a cabbage white butterlfy with a tasty body but with wings that make it impossible to swallow.  What to do?  For as long as I watched the lizard hung on and apparently considered its options- get rid of the wings or give up the prey.  I had to leave before the conclusion of this epic battle but I was surprised to see  the lizard attack such large prey.

Bill Dunson

Goodbye Mr Grosbeak?‏

After several weeks of a "plague" of beautiful rose breasted grosbeaks which had an unplanned diversion of their northerly migration through SW FL, it appears that they have left us and headed to their breeding grounds.  Both males and females have been in our yard up through Monday April 28, but then disappeared.  We have also heard from friends in VA that grosbeaks are passing through their yards so the natural progression of northerly movement is occurring.  

Will there be another invasion of spectacular neo-tropical migrants? Only the weather can determine this with westerly nocturnal winds, but the migratory stream of birds will soon be past if not already.

Bill Dunson