Monday, April 28, 2014

A Plague of Grosbeaks!‏

During the last week of April in SW, FL, we have been undergoing an "invasion" of sorts.  There have been more rose-breasted grosbeaks seen than during living memory.  What is happening?  

These are migrating grosbeaks flying north from South and Central America to their breeding grounds in high elevation and northern latitudes sites in eastern and central N America.  They breed above 3000 feet near our VA farm but we rarely see them in any numbers.  

Why are we seeing so many this year?  It appears that they starting flying from Yucatan with tickets to land in TX, LA, MS, and  AL, but were likely blown off course to the east and landed in FL instead.  Bad luck for them and good fortune for us who can now enjoy their extraordinary beauty.  These birds are hungry and thirsty so if you provide fresh drinking water (especially a drip bath), and food either as fruit (mulberries and strangler figs are best) or sunflower seeds, you will have the opportunity to appreciate them for several days before they resume their journey.

We wish them well and look forward to seeing and hearing them up north when they are singing their wonderful territorial breeding song.  The song is generally described as being similar to the song of a robin who has taken voice lessons.

Bill Dunson

Friday, April 25, 2014

Falcon Rest

(Got these terrific pix with emails from Pat Wright, Photographer and Bill Dunson!)

Hi Bill,
I visited the beach early this morning on Boca Grande and found a beautiful peregrine falcon sitting on a piece of driftwood. Is this the female? I'm sure she was looking for a nice bird to catch. I know these birds don't nest in Florida, but do they migrate from here to Central or South America and would they be doing that now, in the Spring?
Pat Wright

Males and females look identical except that the females are larger. But judging size in a bird that is not sitting next to something of a known size is difficult/impossible.
Bob/Merrill and some friends saw a hawk kill a red knot on the Knight Island beach and I suspect it was a peregrine.

Sea Turtle Mystery on Knight Island‏

Sea turtle recovered on the Spit on Knight Island

When walking the beach on Knight Island I happened upon a sea turtle mystery.  Three ladies who volunteer for the sea turtle patrol were recovering the body of a dead female loggerhead turtle from the surf.  Eva Furner and Pam Neer from the Coastal Wildlife Club found the turtle during their nest survey.  They phoned Lynette Auger, the contact person for Charlotte County, who contacted Cathy Schwartz who is authorized to examine dead turtles and either mark and bury them or turn them over to the county and subsequently state staffs for autopsy.  The three ladies lifted and carried the body from the water to the beach where they could examine it.  (photos below) Surprisingly the body was quite fresh and did not show any marks indicating the cause of death.  The only clue was that the turtle seemed to be lighter than expected.  This suggested a problem with feeding or digestion leading to malnutrition.  Of course sea turtles are returning to area beaches at this time to nest.  It seems strange that a sick turtle would make the migration for reproduction.  So this remains a mystery, why such a healthy looking female loggerhead would be dead on the beach.  Maybe a subsequent autopsy will reveal the cause.  Nesting last year was excellent so we are all hoping for a strong showing again this year which indicates that the sea turtle population is healthy and recovering from a long decline.

Bill Dunson

Magnificent Migrant Yard Birds

Male scarlet tanager
In late spring some migrant birds continue to amaze and delight those who are carefully observant of the new birds in their trees and shrubs. These neotropical migrants are moving northward to their breeding grounds and are sometimes diverted through Florida by nocturnal westerly winds that blow them off course. Particularly striking is the brilliantly colored male scarlet tanager when adorned in his breeding plumage. We enjoyed watching both the bright male and duller female eating fruit of both mulberry and strangler fig. 
Rose-breasted grosbeak (male) eating berries
Blue grosbeaks
Rose-breasted grosbeak (female)

In our yard the presence of rose-breasted grosbeaks at feeders and in fruit trees such as mulberries and strangler figs is pretty exciting since the adult males are brilliant red, black and white. They gorge on the mulberry fruits and stain their bills. The females are camouflaged, the better to protect them when they are sitting on eggs. The blue grosbeaks have a similar bill for cracking large seeds but their color is very different. I was particularly interested in some juvenile males which were molting from brown to their adult blue plumage. The habits of blue grosbeaks are quite different since they are more of a southerly grassland/shrub species compared to the northern mountain/forest dwelling rose-breasted grosbeak. 

A bird that feeds on somewhat smaller seeds is the painted bunting which does winter here but is also now migrating though. It has a much smaller bill which illustrates how selection can modify bill size to minimize competition among species. This greenish bird may be a young male but the differences between adult females and young males can be confusing. 

Painted bunting
Of course the warblers are the stars of the birding world and can be challenging in the fall, but their spring-time feathers are often very bright and distinctive. Here a male redstart stops for a bath in our yard. 

Male redstart, bathing
April and early May in Florida are so delightful for birders since they get to see a parade of colorful and interesting species as they return from a winter in the tropics. It is definitely an exciting time and represents the renewal of life across the whole spectrum of nature. 

Bill Dunson 

Sunday, April 20, 2014

Going Going Gone!‏

When we first came to the SW coast of FL 20 years ago we were mystified by the presence of a common large plover with a light breast on the beaches. Then we realized that this was the winter plumage of the black bellied plover which we had previously known only with its very dark belly along the east coast of VA during its migration to the Canadian Arctic. So this bird loses its black breast feathers in the fall, replaces them with light ones, and re-grows dark feathers in the spring. The process of molting back into a dark breast occurs in SW FL during late April and early May for most of these plovers. Apparently the dark breast is a substantial advantage in breeding, but a decided disadvantage during the rest of the year. The photos show the two extremes and the spotted stage in between as the feathers are molting. 

A spring time change in feathers occurs in many birds, so look around and notice the new breeding plumages present in many species. 

Bill Dunson 

Images of the Crucifix Seen in Nature

Crucifix image on catfish skull
We commonly encounter natural objects which have been interpreted by early Spanish missionaries and even some modern-day observers to resemble the Christian crucifix symbol and associated circumstances.  

For example the inside of the skull of a marine catfish bears a striking resemblance to the crucifix.  

Crucifix orchid with
blue porterweed
The crucifix orchid has even been named for a similar resemblance.  The famous passion flowers named for the passion of Christ are unusually shaped and apparently designed for pollination by large bees.  But various parts of the flower have been considered symbols of Christian theology; the pointed leaves represented the holy lance, the tendrils of the vines represented the whips used to punish Jesus, the ten petals and sepals represented the ten faithful apostles, the radial filaments represented the crown of thorns, the ovary and receptacle represented the Holy Grail, the three stigmas represented the three nails, the five anthers represented the five wounds, the red flower color represented blood, and blue flower color represented heaven.

Bill Dunson
Red passionflower

Purple passionflower

Name That Tern !‏

Caspian, sandwich and royal terns at Sump Pass

A group of terns sitting on the beach at Stump Pass provided a nice clinic on identification.  Can you distinguish the three species of terns shown?

In the foreground there is a single Caspian tern which is larger and has a heavier, red bill with a dark tip. The eight royal terns in the background are common on local beaches and their bills are more slender and generally orange.  The wing tips of the Caspian are darker and it is much rarer along the coast and tends to be found in fresh water areas except during winter migration.  The smaller tern just to the left of the Caspian with a light bill tip is a sandwich tern.  

So after having passed the "Tern 101" class go out to the beaches and study!

Bill Dunson

Thursday, April 17, 2014

The Orioles are Coming!‏

Birds we especially look forward to seeing during migration are the orioles, namely the Baltimore and Orchard orioles.  They are colorful and enjoy feeding on yard plantings with flowers and fruit.  Now in mid-April they have been arriving in our area of SW FL for about a week.   In addition to differences in color, note the different bill shapes in the two male orioles.  The orchard has a shorter and sharper bill that serves it well in piercing flowers to obtain nectar.  It is especially attracted to Cape honeysuckles and Turk's cap hibiscus but also eats fruit.  The Baltimore has a longer and heavier bill and feeds mainly on fruit in our yard, especially mulberries (white in this photo) and strangler figs.  These birds are streaming north, especially along river valleys, and will soon be arriving at our VA farm where they breed in our front yard in a huge maple tree.

Bill Dunson 

Monday, April 14, 2014

Trash Free Seas

This email was sent to the Don Pedro and Knight Island Sea Turtle Patrol, but anyone who walks the beach can participate by monitoring trash accumulation on our shoreline:

Ocean Conservancy’s Trash Free Seas program works on various fronts addressing the  problem of marine debris, taking a holistic approach towards solutions. We are just beginning to understand the effects of ocean trash on marine wildlife and know that sea turtles are often disproportionately affected by plastic pollution and other debris while in the water and on the beach. Very little research and data exist on the amount and type of trash that female sea turtles face when nesting and also what debris obstacles their hatchlings must overcome in their trek to the sea.   We are reaching out regarding a potential collaboration with Don Pedro/Knight Island Sea Turtle Patrol to monitor beach debris in conjunction with existing sea turtle monitoring efforts.

This past summer, Ocean Conservancy partnered with the Wrightsville Beach Sea Turtle Project in North Carolina to obtain marine debris data in existing sea turtle monitoring transects patrolled by volunteers each morning. We equipped volunteers with ocean trash educational materials and our simple marine debris monitoring data form, which they utilized to document and remove debris. The results were quite impressive, and we’re in the process of analyzing the relationship between nesting success/false crawls and debris density.

As we look toward the 2014 nesting season, we’re planning to expand the geographic scope of this project throughout the southeastern United States. Moreover the Trash Free Seas program sees great potential in conducting additional, more robust monitoring along some of Florida’s protected shorelines. As one of the go-to authorities for sea turtles in Florida, we would value the opportunity to chat further about a potential collaboration with your organization during the 2014 nesting season.
If you are interested in learning more about this project, we would love to speak with you further on how we might collaborate. We understand that sea turtle nest monitoring already requires a substantial amount of your time and attention and know that existing monitoring regimens takes top priority. We believe this is an opportunity that will benefit both sea turtle conservation efforts and the investigation into how we might prevent trash from entering our ocean and beaches in the first place.

Please see the attached document [CLICK HERE] which briefly describes the project and outlines how volunteers can contribute. We look forward to hearing from you and thank you in advance for your consideration.

Thank You,

Sarah Kollar
Special Projects Assistant


Sunday, April 13, 2014

Breeding display of yellow crowned night heron

Yellow crowned night herons are commonly seen in salt water areas and sometimes inland also.  The adult male and female are essentially indistinguishable and normally do not show any especially notable behavior. However I saw a heron today (April 13, 2014) which surprised me.  I am assuming it was a male because it engaged in a display in which its back plumes were rotated forward and outwards.This resulted in a very striking posture which I assume was directed towards a nearby female.  
During breeding season there are also two long head plumes and the legs turn reddish.  The overall impression is very much like the exotic birds of paradise of New Guinea and I assume the purpose is the same, to entice a female into mating.

Bill Dunson

The Blues Brothers and Other Backyard Bird Surprises

Blue grosbeak male
April is a time of great excitement among birders since migration of a vast army of birds begins from South and Central America to the US. This predominantly occurs northerly from the Mexican Yucatan Peninsula across the Gulf of Mexico to the coast between Texas and the FL panhandle. However when a weather front passes through, producing strong winds and rain from the West and Northwest, many birds can be forced to the east of their typical course and land in Florida. This is bad news for the birds since it is stressful, but good for Florida birders who periodically get to enjoy a "fallout" of marvelous birds from the night time skies. The next morning the birds can be exhausted and in need of rest, fresh water and food, and thus easier to observe than normally in a dense forest. 
Blue grosbeak and indigo males

We have recently had what I call a "mini-fallout" of birds along the SW FL coast. In our yard on Manasota Key we have had the pleasure of observing beautiful migrants including warblers such as hooded, parula, prairie, and even the rare Kentucky, orchard and Baltimore orioles, summer and scarlet tanagers, blue grosbeaks, a peewee, and lots of ruby throated hummingbirds. 

We maintain water drips that attract the birds by sight and sound and saw a pair of birds attracted to the water that might be termed the "blues brothers." The adult male indigo bunting turns a bright blue this time of year and although a few spend the winter in FL, most migrate in from the south heading to their breeding grounds to the north. The male blue grosbeak differs in having a much larger bill, a different blue color and rufous wing bars. This individual also appears to be molting its brown juvenile feathers and replacing them with blue ones. As its name grosbeak implies it also has a very large bill, the better to crack large seeds. 
Summer Tanager

But it is interesting that the indigo bunting always loses the adult male blue color in winter, whereas the adult blue grosbeak remains blue all year. This mirrors the difference between male plumage color in summer (permanently red) and scarlet tanagers (seasonally red only) and shows how strategies for camouflage and male-male territorial aggression vary even among closely related species. 

In our area of Florida we have few hummingbirds except during migration, so we enjoy them very much when we can see them. We have lots of nectar-rich red flowers planted for the hummers such as coral honeysuckle, firebush, Turk's cap hibiscus, shrimp plants, and cape honeysuckle. This particular hummer appears to be a female rubythroat, yet it has an unusual yellow throat patch which is likely due to pollen. 
Orchard oriole male collecting nectar

Orchard orioles are particularly attracted to local yards with flowers and fruit during migration; they seem to prefer gathering nectar from Cape honeysuckle and Turk's cap hibiscus. Orioles and summer tanagers are very fond of fruit such as ripe mulberries and strangler figs. This male orchard oriole is piercing a cape honeysuckle flower to obtain the nectar. This flower is derived from South Africa where its peculiar shape is well designed to accommodate the curved bills of the local sunbirds. Hummingbirds may be the only native birds that can reach the nectar the normal way down the corolla tube. Local birds and some insects such as honeybees pierce the base of the flower and steal the nectar. 

So enjoy this amazing time of year when many thousands of spectacularly colored birds are passing through our yards. This is a temporary show that will quickly pass as the birds move to their northern breeding grounds so don't miss it. 

Bill Dunson 

Saturday, April 5, 2014

Red breasted mergansers hit the beach‏

Female red breasted merganser

Male red breasted merganser
Sometimes while walking the beach you encounter an unusual bird, in this case both male and female red breasted mergansers were either resting (females) on the beach or feeding for small fish in the surf (one male).  This is a rare opportunity to study this species up close and personal since they normally are found out in the bays and are not too approachable.  These "beach bums" have become somewhat used to people walking along the shoreline.

Bill Dunson

Wednesday, April 2, 2014

Amazing Backyard Arachnids‏

Top Left: Green Lynx female in nursery web
Bottom Left: Spiny Orb Weaver
Right: Banana Spider

One of the animal groups that people have the most difficulty in appreciating must be spiders.  Even snakes seem to have more admirers than these creepy arachnids with their eight hairy legs.  Why is this?  Could this be an innate fear from our distant past or simply something learned from our parents and peers?  Although all have a poisonous bite, few are of real danger to humans.  So I have been systematically examining the arachnids that I come into contact with to learn more about them.  They are a very common predator, indeed remarkably so if you look at the number of webs in a field on a misty morning, and this does not count the species that hunt without a web.   So here are a few examples from my backyard in Florida.

Orb weavers are a diverse group which makes spectacular webs with concentric rings of sticky silk that catch prey.  There is one particular large orb weaver which lives outside our front window and spins her web most warm evenings.  I say "her" since most spiders we encounter are the larger females; males tend to be small and inconspicuous.  This orb weaver males a new web every night and takes it down the next morning.  On this one occasion she caught a large cone headed grasshopper and is dining on its flesh which is liquified by the injection of enzymes and then sucked up by the spider.  These spiders show us how attached to one place they are since I have sometimes moved them away from a doorway and found that they return.

A very large spider that you will not ignore is the banana, golden silk spider or Nephila.  It is huge and is said to have the strongest silk of any arachnid. 

The green lynx spider is beautiful and shows a strong maternal instinct in caring for her large brood while abstaining from eating.

The Gasteracantha or spiny orb weaver is quite common and tends to end up on your face as you walk around the yard.  It's bizarre shape seems to be designed to deter predation by birds.

Top Left: Whip Scorpion with Josh Dunson.
Bottom Left: Whip Scorpion.
Right: Orb weaver eats conehead katydid

One of the spectacular spider relatives in our yard on a sandy barrier island is the impressive whip scorpion or vinegaroon, which lives in leaf litter and shallow burrows.  They are representative of migrants from western N America such as rattlesnakes, racerunner lizards and scrub jays that likely moved to FL when the sea level was much lower.  They are completely harmless to humans and only spray acetic acid when disturbed.  But they are fearsome predators of roaches and other insects and deserve protection for this reason.  They represent useful members of the ground litter community which are highly beneficial in controlling noxious insects.

So learn about your beneficial neighbors the arachnids and give them some respect.  They represent very useful members of invertebrate predatory niches which eat many troublesome insects and can be powerful friends in the management of your yard with minimal use of pesticides.