Wednesday, March 26, 2014

A Brief Excursion into a Northern Spring‏

Azure butterfly
Those of us who are snowbirds in Florida generally avoid heading north until the weather is pretty warm in the mid-northern latitudes.  However family business took me to NC/VA in mid March and I had a pleasant if somewhat chilly time exploring the natural history of some early spring ecosystems from the NC Piedmont to the VA Blue Ridge.  There were numerous signs of spring in the activities of animals but the icy grip of winter was still tenaciously clinging to the landscape.  
Bill's cabin at his farm in Chapel Hill, NC

A view of my "contemplation cabin" on our VA farm shows the lack of leaves on trees and the small amount of green vegetation.  Yet there were several amphibians breeding in the ponds- the wood frogs had laid eggs, spring peepers were calling, and the newts were showing reproductive interactions.  Wood frog eggs are usually laid together in large communal masses on the sunny side of ponds at the surface to take advantage of the
Wood frong eggs in pond
 warmest areas; this serves to accelerate development of the tadpoles.  Many ponds are ephemeral and it is advantageous for the frogs to metamorphose sooner rather than later.

On sunny days there were butterflies in flight; here I show a beautiful spring azure that was catching some sunny rays in a spot protected from the wind.  Some other insects were still awaiting warmer weather- a mantis egg case found in a bush will not hatch probably for several months.
Mantis egg case

Birds are quite indicative of seasonal changes.  Tree swallows suddenly showed up one day at our farm although we believe that these are birds that will head further north to breed and be replaced by later migrants that are our own breeding birds.  Hermit thrushes were present at much lower elevations than they will be found when they later breed.  
Yellow-rumped warbler

Yellow-rumped warblers were also staging at latitudes lower than their breeding sites, awaiting better weather for northerly migration.  "Rumps"  are better suited than any other warblers for remaining fairly far north during the winter and migrating earlier since they can feed on berries or even suet.  Note the icicles hanging on this suet feeder in the NC Piedmont on March 14!  It is a risky proposition for birds to migrate north early since they can often be caught by ice and snow storms.  Perhaps the opportunity to reach breeding grounds earlier and to avoid long migrations to the tropics in winter compensates for this type of mortality. We can help them out by planting bushes that provide winter and early spring supplies of small fruits that they enjoy such as wax myrtle and various viburnums. 

So observe and enjoy the signs of spring wherever you are located and think about the myriad and different adaptations of animals to the seasonal changes that are occurring.
Newt in pond
Hermit thrush

 Bill Dunson

Tuesday, March 25, 2014

What a Beak!

American oyster catchers are one of my favorite shorebirds due to their amazing and flamboyant beak.  It is a precise tool to crack open clams and oysters by inserting the chisel-like bill in between the open shell valves and cutting the muscle that closes the shells.  But they are rare enough in SW FL to be exciting to see.  In one of our favorite haunts on Delmarva, Chincoteague Island, 
we used to watch them at dusk gathering in flocks to fly to roost and emitting an amazing cacophony of sound.  An very impressive and beautiful bird.

Bill Dunson

Tuesday, March 11, 2014

Views from Myakka River State Park, FL

Sand Hill Crane with Young Colt 3.10.14
Myakka River State Park is always a delight in any season but early spring is certainly wonderful.  My son was visiting and he tried a long run on the 27 mile Myakka Trail that snakes around the perimeter of the park.  Fishermen were enjoying throwing in a line and they were accompanied by an interested avian observer (great blue heron); which one is the better fisherman?

Other wildlife seen were large flocks of turkeys in which the males/toms were strutting their stuff for the females. Sandhill
Barred Owl at MSRP 3.7.14
cranes already have their babies (called colts strangely enough) in tow and are teaching them how to catch food.  A pair of barred owls was hooting in the oak trees in preparation for breeding.

My wife is an avid birder and she was very exited that we found the first of season Louisiana water thrush, an early migrant from the south.  This bird is one of millions of birds soon to be flying across the Gulf to reach breeding territories in the US.
Great Blue Heron with Fisherman MRSP 3.10.14

Bill Dunson
Louisiana Water Thrush, Clay Gully, MSRP 3.10.14

Male Turkeys Strutting at MSRP 3.10.14
Bill's son Billy at end of 26-mile run at MSRP 3.10.14

Crabs Aren't Just A Dinner Time Favorite‏

Fiddler Crab on Thornton Key
Humans are mainly appreciative of the delicious taste of crabs, and not particularly of their importance as ecological kingpins.  But the numerous crabs present in saline habitats are often extremely important in their food webs.  Fiddler crabs are often used as bait and can be numerous on muddy tidal flats.  They also serve as food for birds such as yellow crowned night herons and have a large role in transfer of nutrients from detritus and algae to  higher levels of the food web.  Scientists have long known that they have a distinct internal tidal "clock" that allows them to know when to come on the surface to forage.

Blue Crab Male
Blue crabs are not just delicious, their role as predators/scavengers in shallow water habitats is significant and removal of too many may have serious ecological impacts on the soft bottom community.  Certainly they are one of the best defended invertebrates and use their claws very effectively.  The photo illustrates one of the safest ways to hold a blue crab without being pinched, by the rear swimming flipper.  Males have blue claws and females red-tipped claws; in essence the females have "lipstick" which attracts the attention of males.  

Red Mangrove Root showing Tannins
Anytime you are in mangrove areas you will notice a small crab scurrying around in the trees.  This crab, Aratus, feeds on leaves, detritus and some animal protein and is thought to have an important influence not only on nutrient cycling in mangrove forests, but to affect the types of mangroves present.  A much rarer and larger crab in our area of SW FL is the mangrove root crab, Goniopsis cruentata.  I found one of these for the first time recently in Oyster Creek.  The scientific literature indicates that the feeding of this crab can increase the number of red mangroves present in the tidal forest relative to white and black mangroves.   This occurs because it does not like to eat red mangrove seedlings with high amounts of tannins.  You will note that the mangrove root shown in the photo is quite red inside with tannins. 
Crab mangrove root Goniopsis cruentata
 in Oyster Creek at 775 bridge 2.22.14
 These chemicals not only can be used to tan animal hides, but will greatly reduce the ability of an animal to digest its food by binding with proteins in its gut.  Humans have figured out that milk added to coffee will bind to tannins and decrease the bellyache from their ingestion.  The mangrove root crab is likely only an occasional tropical visitor to our shores. 
You will be very lucky to see one.  I ran into this individual while walking a trail that I had walked many times before.  This proves the point I often make which is that repeated visits to the same natural areas will yield interesting bits of natural history gradually over time.     

Bill Dunson

Saturday, March 8, 2014

Go Ahead and Make My Day

Alligator basking on bank of the Myakka River at MRS Park 3.7.14

My! what big teeth you have...
While walking along the banks of the Myakka River I came across this "smiling" alligator.  The toothy look did not seem to be aggression but possibly a matter of personal hygiene to allow the sun to dry the inside of its mouth and reduce the growth of algae.  But the dental equipment designed for grabbing and holding prey (but not chewing it) is impressive!  To bite off a piece of large prey the famous "death roll" is necessary to twist off a chunk.

Bill Dunson

Unusual American lady butterfly

American Lady Butterfly at Myakka River State Park 3.7.2014
This American lady butterfly observed at Myakka River State Park has a very unusual wing  pattern.  It appears that a portion of the right forewing is lacking the scales that  provide color.  I do not think they are worn away but actually missing since the butterfly otherwise appears fresh and not particularly worn.  But this illustrates how the wing itself is transparent without the overlying scales.

Bill Dunson

Raccoon trouble heading your way‏

Raccoon babies at Myakka River State Park 3.7.2014

Raccoon babies at Myakka River State Park 3.7.2014

Raccoon mom & 4 babies crossing the road - MRSPark 3.7.14
This mom raccoon and her four large babies were crossing a road in Myakka River State Park.  Raccoons are cute and delightful but can be big trouble around the backyard where they raid garbage cans, eat the dog food, flip over bird baths, sleep in the attic and generally raise havoc.  The loving care shown by this mom of her large brood shows how parental care transfers knowledge from one generation to the next.

Bill Dunson

Thursday, March 6, 2014

A Rare Mangrove Snake

I came across this mangrove snake on Knight Island, Charlotte County, FL.  It is a dark phase (there is a reddish phase) with the classic and beautiful belly with a central row of white spots.  

This is a rarely seen, fish-eating,and harmless snake which is mainly nocturnal and limited primarily to salt water habitats.  A salt marsh form is found to the north and a fresh water relative (the banded water snake) inland.  It is quite unusual in being able to tolerate salt water, apparently without a salt gland.  It is a great example of coastal speciation just within the salt water fringe.  The mangrove buckeye butterfly is a similar case.

Bill Dunson

Saturday, March 1, 2014

Too Much Trouble for Lunch?

Maybe this great blue heron has met its match? This gobbleguts of the avian world is having trouble swallowing a banded water snake. The tussle for life and death continued for as long as we watched at Babcock Webb WMA in FL. The problem seems to be that the snake does not want to be eaten and is holding the bird's bill shut! But this illustrates how the heron is willing to eat anything it can swallow. 

Bill Dunson 

Can Exotic Norfolk Island Pines be Beneficial ?‏

Osprey Nest in a Norfolk Island Pine
Various coastal communities and parks may remove, kill or ban the planting of Norfolk Island Pine (NIP). This is due to their being non-native, because of the potential hazard in storm-prone areas, and to results of the hard freeze of 1989 in more northern areas, when a number of Norfolk Island pines died. 

In response I offer my personal experience from SW FL. I live on Manasota Key in Englewood, FL, in Charlotte County, just north of Punta Gorda through which hurricane Charlie passed on Aug. 13, 2004. It was a very narrow but strong storm and caused the loss of many trees including Australian pines. To my knowledge few NIP were blown down! Instead, perhaps due to their conical shape (largest at the bottom and rather pointed at the top) and strong trunk and roots the trees survived. Many of the branches were wrenched off but they re-grew due to trunk sprouting. A report on tree damage caused by hurricane Charlie on Sanibel Island provides a remarkable photo of a NIP trunk with no branches left. Although the report recommends against planting of NIP, they provide no evidence of tree fall. 

Eagle's Nest in NIP: S. Manasota Key
We have a tall NIP immediately over our house built in the mid 50's and I have never lost a minutes sleep worrying about the tree coming down. This tree does produce cones almost every year and the fertile seeds do produce seedlings, which are however very easy to pull up. Apparently this reproduction is somewhat unusual. 

As a retired biologist I spend a lot of time studying how to improve wildlife habitat under the conditions imposed by human occupation of the landscape. Norfolk Island pines are ideal for providing nesting habitat for ospreys and eagles along the S FL coasts where humans dominate the ground level of the habitat. So if you want raptors to nest you must provide tall trees. If you dogmatically eliminate exotic trees such as these Norfolk Island pines which are ideal nesting habitat, you will have few if any nesting raptors since there are not any native trees which will survive and grow to a sufficient height within a reasonable time frame to serve this purpose. Data are scarce but it may take slash pines in this area more than 100 years to reach a size adequate for eagle nests. These tall Norfolk Island pines also provide useful habitat for other birds and animals, they grow fast, and they occupy a small ground footprint relative to their height. I would not recommend "topping" them since the regrowth may overbalance the tree and provide an area of weakness when exposed to strong winds. 

Norfolk Island Pine with Osprey Nest, Manasota Key
I suggest that the rigid dogma of "evil exotics" be replaced by a more pragmatic and wildlife-friendly philosophy which in specific instances uses exotics IF they provide more benefits than problems. Every plant, both native and exotic, should be carefully evaluated for its advantages for wildlife before planting or removal. For example, the killing of Australian pines within Stump Pass State Park caused a nesting eagle pair to leave and re- nest in a Norfolk Isl pine in a private yard just outside the park, where the homeowner subsequently cut the tree down because of the nuisance of people coming to watch the eagles! 

Bill Dunson