UF/IFAS Okeechobee County Extension Service

458 Highway 98 North

Okeechobee, FL 34972-2578

Phone: (863) 763-6469

E- mail:  dfculbert@ifas.ufl.edu

February 8, 2007

Feature Article - for release the week of February 11, 2007

Dan Culbert - Extension Horticulture Agent

Snowbird invasion

 

A look at this week’s calendar shows several important events like Valentine’s Day, Lincoln’s birthday and the most important of all - Friday’s deadline to enter exhibits in the Okeechobee County Fair.  It’s easy to be distracted this time of year.

Lots of things are flying around town, especially all those snowbirds that have ventured down to escape the cold winter up north. Last week a bunch of these visitors took over our office parking lot.  They were very busy drinking our water, using our “facilities”, and consumed a variety of snack foods found nearby. 

No, I am not talking about hordes of slow-driving tourists, but referring to flocks of American Robins.  These birds are a traditional sign of spring, and are now starting their march north.  Some ideas on why we have these “Hitchcockian” invasions of migratory songbirds are the subject of this week’s column.

Basic Bird Biology

Wildlife biologists outline some basic rules for all successful wildlife management: food, water, and shelter.  If a critter is to be encouraged, make sure it has all three of these basic needs.  Likewise, if that wild thing is bothersome, do what can be done to reduce or eliminate those habitat requirements to send that creature to greener pastures.

In the case of this familiar North American bird, the orange-breasted American Robin (Turdus migratorius) is a common “snowbird” species here in Florida.  In general, they migrate south for our warmer temperatures and abundant food supply.  Once Punxsutawney Phil gives the all clear for winter to end, this traditional sign of spring begins its annual migration back north.

What makes Florida such an attractive winter mecca?  Robins prefer open places where there the habitat needs can be met.  Rather than fields and farms, robins prefer more urbanized locations. Around many Florida Yards, the landscapes and gardens provide places to hide from predators, shrubs and trees have generous supplies of fruit, and those lawn sprinklers and winter rain showers make lots of puddles for drinking and bathing.

Robins will commonly breed in the northern tier of states and Canada, but more recently have extended its breeding range into parts of Florida.  A look at range maps show that winter and summer bird populations are very much like snowbirds.  However, an occasional Yankee stays down here to build a nest and raise a family in the Sunshine state.  (Sounds like people, right?)  

Winter Feeding 

As a traditional sign of spring, we have become used to the idea that robins will hop around on grassy lawns and pull up a yummy worm.  Spring marks the breeding season, when robins build their nests, lay a clutch of 3 or 4 baby-blue eggs.  Robins will feed their hatchlings delicious earthworms, snails, or soft-bodied insects grabbed from the ground.  These food sources are rich in proteins, needed for building the strong bodies of the developing birds.

"The early bird gets the worm".  Robins may eat lots of worms and bugs when breeding, but generally are fruit eaters when visiting Florida.  Photo (c) Jerry Curtis

This winter visitor to Houston Texas is chowing down on the fruit of Yaupon Holly . The fruit looks similar to that of our invasive weed, the Brazilian Peppertree.  Photo: (c) Kathy Adams Clark

Our local observations with the robin are somewhat different: down here they concentrate on wild and cultivated fruit. I’ve found suggestions that flocks of robins are considered pests by some fruit growers.   While robins may eat some field field-grown strawberries if other wild food sources are unavailable, research shows that only 4% of their diet is cultivated fruit.  In contrast, 42% of their diet is insects.  For small fruit growers, harassment and coverings are the best answer because as migratory birds, it is against Federal law to kill them.

If you have seen these winter flocks of robins, picture the location and recall the kinds of shrubs and plants nearby.  Very often, this includes a common red-berried weedy tree that most locals have come to hate – the Brazilian pepper tree. At this time of year, this weed is still loaded with the small fruits, and is therefore very attractive to foraging robins and other fruit feeding birds. 

After they feed on Pepper-trees, the robins will perch in fencerows, tress, shrubs, or even take a rest on powerlines.  That’s where they do their “business”, leaving behind their calling cards, including the seed from the pepper tree.  Look carefully at these spots in midsummer, and new seedling pepper trees will be seen, courtesy of snowbirds like the American robin.

The other habitat requirement is water.  A low spot in our office’s parking lot makes a great puddle for birds to get a drink or take a bath.  The flock that came by took full advantage of the rainwater left behind by the recent winter storm that blew though Florida.  Near my home, I have also seen flocks of robins visiting a communal bathtub – a low spot in a street where the homeowner has their lawn sprinkler set to irrigate more asphalt than turfgrass.

 

Mass Migrations 

A co-worker made a comment the other day that he’s never seen a flock of robins like this before.  Actually, Florida flocks of winter robins have been documented over the years. One reference dating from mid-February,1897 recalls a flock of hundreds of robins seen in the Cape Canaveral area.  I found a more recent stories by a Tampa area reporter and a Naples news writer.  Other references also suggest that these birds consume slightly fermented pepper berries, resulting in some tipsy flight patterns by intoxicated robins.

For those interested in encouraging these red-breasted fowl to stay around, be advised that birdhouses will not keep them in town.  Encouraging appropriate habitat would be a better approach, but remember that the nature of robins is migratory.  Enjoy those mass migrations of robins when they appear here, remove the volunteer seedlings they leave behind along the fencerows and powerlines, and dream of times when the snowbirds return to their northern breeding grounds.

I’ve placed photos and links to more information on our Okeechobee web page, http://okeechobee.ifas.ufl.edu.  If you need additional information on American Robins, please email us at okeechobee@ifas.ufl.edu or call us at 863-763-6469.  Local residents can stop by our office at 458 Hwy 98 North in Okeechobee, and visit our Okeechobee County Master Gardeners from 1 to 3 PM on Tuesday afternoons.  GO GATORS!

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Trade names, where used, are given for the purpose of providing specific information. They do not constitute an endorsement or guarantee of products named, nor does it imply criticism of products not named. The Florida Cooperative Extension Service - Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information, and other services to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin.  Florida Cooperative Extension Service / IFAS / University of Florida.  Larry A.  Arrington, Dean Last update: 04/09/2008 .  This page is maintained by Dan Culbert 

Bird Monitoring programs need volunteers.  Here are two that can use your bird-watching talents: 

Florida Bird Monitoring Program http://bird.ifas.ufl.edu:8101/WildLife/index.html

About American Robin Migration  http://www.learner.org/jnorth/tm/robin/AboutSpring.html  

 

references

Anonymous.  Thrushes / American Robin.  http://goodfelloweb.com/birds/perching/thrushes/robin.html 

Avery, Michael L  Robins and Berries.  Gainesville: USDA Wildlife Services National Wildlife Research Center, 3/2003. http://strawberry.ifas.ufl.edu/BerryVegMar03.htm#Robins%20and%20Berries

Hunter, William C. American Robin Turdus migratorius [Florida's Breeding Bird Atlas]. Tallahassee: Florida Fish and Wildlife Conservation Commission, 2007.  http://myfwc.com/bba/amro.htm

Ochoa, Julio. "A 'gift' that's for the birds." Naples Daily News, 2/19/07. http://www.naplesnews.com/news/2007/feb/19/robins_bringing_unwelcome_gifts_form_invasive_pepp/?local_news 

Sallabanks, R., and R. C. James.  American Robin (Turdus migratorius). In The Birds of North America, No. 462 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA. 1999. http://www.birds.cornell.edu/AllAboutBirds/BirdGuide/American_Robin_dtl.html

Sauer, J. R., S. Schwartz, and B. Hoover. The Christmas Bird Count Home Page. Version 95.1. Laurel, MD: Patuxent Wildlife Research Center, 1996. http://www.mbr-pwrc.usgs.gov/bbs/cbc.html

Sauer, J. R., J. E. Hines, and J. Fallon. The North American Breeding Bird Survey, Results and Analysis 1966 - 2005. Version 6.2.2006.  Laurel, MD: USGS Patuxent Wildlife Research Center, 2005. http://www.mbr-pwrc.usgs.gov/bbs/bbs.htm

Vandaveer, Chelsie.  "Has help arrived to control Brazilian peppers?"   Killerplants.com, April 23, 2003.  http://www.killerplants.com/renfields-garden/20030423.asp   

Varian, Bill.  "Drunken robins bobbin' along." St. Petersburg Times, January 26, 2005. http://sptimes.com/2005/01/26/Tampabay/Drunken_robins_bobbin.shtml?ss