Wednesday, August 19, 2015

How to Attract Butterflies with Salt‏

Red spotted purple on sweaty yard shirt!

Yellow swallowtail on dung

When you think about ways to attract butterflies, this generally involves planting flowers that supply nectar for the adults or leaves for the caterpillars.  However an alternative technique is to offer salts, especially sodium, which butterflies crave because their vegetarian diet is rich in potassium but not sodium.  This is different from the ancient myth that you can catch a bird by putting salt on its tail.  It is no myth that butterflies have a powerful attraction to salt.

You will notice this fact if you carefully observe the behavior of butterflies.  For example this week I was biking along a rail trail which also allows horses.  It was immediately obvious that butterflies are attracted to the dung of horses.  I attach a photo of a tiger swallowtail that was "puddling" on horse dung to obtain the salt rich fluids, which may be disgusting to us, but life-giving to salt starved butterflies.

After working in the yard I took off my sweat-soaked shirt and hung it on a rail to dry.  A red spotted purple butterfly was attracted to it, presumably to drink the salt-rich sweat.

It seems quite likely that butterflies recognize the smell of dung and sweat and seek out the sources to obtain salts.  I have even had butterflies light on my arm and drink the sweat.

You can also put out a patch of damp sand with sodium chloride added as a butterfly attractant.

So buy a horse, or get sweaty, and bring those butterflies into your yard!

Bill Dunson

Tuesday, August 18, 2015

Shark tooth hunting on Palm Island

It is never too late to look for a few more shark teeth !  Annette Dunson, visiting from Salt Lake City, gets in a last look for shark teeth along a secluded Palm Island beach just before dark.  Recent stormy weather has been good for churning up the sediments that reveal fossil teeth and bones.

Photo by Bill Dunson Jr.

Monday, August 17, 2015

Summer Pond Life

Female bullfrog
Nothing expresses summer time more than the whirl of life around a pond. There is an intensity of competition and predation, but also great beauty among the intricate web of life that revolves around a small body of water.  
Fishing spider
The fishing spider lives at the intersection of air and water by running across the surface tension and also diving under the water to capture tadpoles and small fish.  Dragonflies are completely aerial predators as adults but live as nymphs underwater.  Although relatively primitive insects, they have complex behavioral patterns governing their reproductive patterns.  
Common green darners ovipositiing
The eastern pond hawk illustrates the striking difference in color between the male and female.  (see photos below) One day I caught a pair of green darners in the process of laying eggs with the male (on right with bluish abdomen) contact guarding the female (holding her behind her head) while she laid.  This insures the male that his sperm will fertilize the eggs.  
Male bullfrog
Frogs insure their paternity by external fertilization of the eggs as they are laid. The male bullfrog maintains a territory in part by calling loudly and the external ear drum of the male is much larger than that of the female, the better to evaluate the quality of the call of rivals.   Compare the size of the ear drum in males and females against the size of the eye.  

Green frog
Green frogs occur in the same ponds and can be distinguished from bullfrogs by a lateral fold in the skin; the male also has an ear drum larger than its eye.  
Snapping turtle
A top predator in most ponds is the snapping turtle which will eat almost anything it can catch.  They roam widely to reach remote ponds and are ubiquitous inhabitants of fresh water.  Their shell is greatly reduced in comparison with a box turtle since their defensive capabilities are considerable. They often bask to raise their body temperature to accelerate digestion.
Northern water snake
The northern water snake is also wide spread and often feared by humans due to its resemblance to the water moccasin, which does not occur in the mountains and northern latitudes.  It is primarily seen while basking on rocks and logs.  This large female likely enhances the development of her young by raising her body temperature.
Eastern pondhawk female
Try sitting by a small pond for a while and enjoy the show!  It is a fascinating illustration of how one tiny habitat can provide a home for a myriad of creatures that are each dependent in some way on aquatic habitats.  I find it especially interesting how this web of life fluctuates on both a daily and seasonal basis, and varies depending on whether fish are present.

Eastern pondhawk male
Bill Dunson Galax, VA and Englewood, FL 

Limpkin alert on Palm Island !

My son Bill Jr. who is visiting from Salt Lake City recently photographed (8.8.15) this limpkin at the pond just inside the Palm Island Resort gate.  I have never seen one of these on Palm or Don Pedro Islands.
They are uncommon but typically found around inland marshy fresh water habitats, such as the Celery Fields or Myakka River State Park,  where they primarily feed on apple snails and sometimes fresh water clams.
So keep your eyes open for this rare visitor to the islands.
Bill Dunson

Tuesday, August 11, 2015

Grandson catches nice snook "on line"‏

We have had trouble for years getting some of our grandsons from Utah to come visit us in Florida.  They are reluctant to leave their friends and electronic toys behind for some quality time on the beaches and bays.  So when 18 year old Josh agreed to come with his family for a trip to FL recently we were happy and hoped that he would have a good experience.  

Josh caught a very nice snook at Stump Pass and it seems that he might have experienced one of those moments when a person realizes that although real life with a fishing line may be less predictable than computerized "on-line" fun, it can be a lot more exciting than cyber-life !

Bill "Grandpa" Dunson

Tuesday, August 4, 2015

Biking for Natural History‏

Although the typical means of enjoying nature would be by walking, I have found that biking can be a great way to find natural wonders in any area which has biking trails.  The rails to trails paths are ideal since they tend to be easy to ride while watching the passing nature show.  One of our favorites is the New River Trail State Park in VA which has repaid repeated rides on the same trail segment to spot daily and seasonal changes in natural history.

Some butterflies tend to congregate on trails as open spots in the forest.  This eastern comma seemed to be sunning itself with open wings as did a nearby red admiral.  
However a clubtail dragonfly, a black shouldered spiny legs, was also admiring the red admiral and swooped over, caught and ate it !   

Another feature of this trail which attracts butterflies is the prevalence of horse dung which provides sodium salts; this male spicebush swallowtail seemed to be sipping fluids from dung in a behavior termed "puddling."  

Male box turtle plastron

Box turtles are often seen on bike trails, perhaps attracted by the sun light and/or a place for egg laying and interactions with other turtles.  Males typically have a red iris and a concave lower shell, the plastron. 

Females have a darker iris and a convex plastron. 

Female box turtle
Animals sometimes do unexpected things, as this male box turtle observed swimming in a pond. 

Although he was an inefficient swimmer, he did manage to cross the pond safely while floating like a cork. 

Box turtle swimming in pond
Since box turtles live to a considerable age, more than 50 years, and reproduce slowly, they deserve our respect and care for their well being in coping with the dangers of the modern world.

Great egret in New River
We observed a great egret along the New River Trail and became excited by this since we had not seen one this year in the mountains of VA.  This indicates that not only is the value of real estate determined by location, but also the value of a bird siting.  In FL and along the SE coasts the great egret is a "trash bird" hardly worthy of notice.   Yet in the Blue Ridge Mountains it is a regular but uncommon visitor which attracts some attention.  It is also one native species that is coping fairly well with the changes made by humans to the planet, since it seems to be able to respond in a flexible manner to feeding opportunities.  

Red admiral butterfly
So get that bike out of the garage and take a ride on the wild side, cover more territory than you can on foot, and scan the surroundings for interesting natural history occurrences.  It is fun, healthy and a very productive way to observe nature.

Bill Dunson 
Galax, VA and Englewood, FL

Mom vireo feeds baby in front yard‏

On July 23 we found a young yellow-throated vireo baby on the ground under an old maple near our home and heard a second one nearby.  We thought it must have fallen out of the nest that was up high in the tree since it couldn't fly and had difficulty moving about on the ground.  The next morning we heard a baby calling from a viburnum bush next to our window.  We were happy to see a tiny vireo perched about 2 feet above the ground and later saw a parent feeding it.  By afternoon we saw it fly about 30 feet to another shrub, then later it was calling about 40 feet from that with a parent fussing nearby.  So all is well so far with one of the babies and hopefully our vireo will nest near our home again next year.  

It appears that the behavior of jumping out of the nest may be instinctive, possibly to distract predators from finding a group of youngsters together.  It does expose the youngsters to other dangers inherent in flying/jumping individually from bush to bush, but undoubtedly provides flying practice.

Margaret and Bill Dunson
Galax, VA

Canadian migrant arrives early on the New River

With the arrival of August it seems that summer is almost over, most birds have finished breeding, and cooler weather must be coming soon.  But one of the surest signs of the approaching end of summer is the first arrival of migrating birds that breed in the far north.   While on a bike ride to Byellsby Dam along the New River Trail in SW VA on July 26, I was surprised to see a solitary sandpiper feeding along a mud flat.  It would appear that this bird has already bred in the far north and is now returning to its winter home in Central or South America.    

It is always surprising to me that the breeding of these long distance migrants is so quick, and the distances traveled so great.  Conditions in Canada must be very conducive to breeding to justify the dangers of migration to accomplish this rapid reproductive cycle.  Yet how often do we fail to express our wonder at such amazing feats of avian athleticism and the remarkable evolutionary pathways that led to such migratory behavior?      

Bill Dunson