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Tuesday, March 18, 2014

Two Bird Banding Demonstrations at Prairie Ridge


Gathering Scientific Data 
from our Feathered Friends


Over the past few years I've had two opportunities to observe the banding of song birds at Raleigh's Prairie Ridge EcoStation (see link), a roughly 45 acre piece of nature that is home to a variety of birds, mammals, reptiles, amphibians, insects, and plants.  The first was a chilly and overcast Saturday March 26, 2011.  On a sunny and warming morning of March 8, 2014, I had my second chance.  This post consists of pictures from both events.
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Early in the morning licensed bird-banders from the NC Museum of Natural Sciences and NC State University set up several mist nets in strategic areas where birds fly from one large thicket of brambles, vines, and grasses to another. 

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Below is a Carolina Chickadee perching on a blackberry cane in a thicket along an old fence-line at Prairie Ridge.
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Below is a White-throated Sparrow hung up in a mist net, a very fine net supported between two poles in the fashion of a badminton net.  There are two color forms (or morphs) of White-throated Sparrows.  This is a white-striped individual which "tend(s) to be more aggressive and less parental than the tan-striped birds" (see reference).

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The bird-banders gently and carefully removed the birds one by one from the netting and placed them individual small cloth bags to keep them calm.  



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Once the birds were collected, the crew made their way to a screened-in classroom where an array of equipment was arranged on portable tables.  Below one bird-bander prepares to retrieve a bird from its cloth sack, while a second uses special pliers to apply a small numbered aluminum band to the leg of a White-throated Sparrow, and a third records the nine-digit band number on a log sheet along with the date and location of the capture, the species, the individual's weight, wing length, presence of fatty deposits, and other data collected from the sparrow.




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Here a White-throated Sparrow is being checked for fat deposits on its chest.

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The wing feathers are inspected for wear and growth since the last feather molt.

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This freshly banded White-throated Sparrow is ready for release.  Notice its distinct white throat, the white stripe above the eye, and the bright yellow "lore" between its eye and beak.


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Another species of sparrow that was banded is a Field Sparrow.  It is a smallish bird with a rusty crown, a gray face and a pinkish bill.


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This Northern Mockingbird is mostly gray with dark gray and white on its tail and wings and a very yellow iris.


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The Mockingbird his having his wing length measured.  Mockingbirds are known for their aggressive behavior toward other birds (cats, dogs, and people, too, if you get too close to their nests).  But they are best known for their ability to mimic the songs of many other birds as well as frogs.
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A bird-bander blows through a straw to part the birds chest and belly feathers to check for fat deposits under the skin.  This gives an indication of how well nourished the individual bird is.  Birds that will be migrating northward in the Spring will start earlier if the have been able to store plenty of fat reserves.


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Another piece of data collected is the bird's weight.  To accomplish this a 35mm film a canister or a pill bottle is used to confine the bird.  This container is set on one of the available portable electronic scales and the scale set to zero. The bird is place head first into the container and weighed.  

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This is a Brown thrasher with its head in a pill bottle being weighed on an even smaller electronic scale.  A well used pair of band pliers is in the foreground.
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After banding the bird and recording of all needed measurements and data, this Brown Thrasher is ready for release.  Notice its bright yellow iris and the rusty brown crown of its head. It has streaks of dark brown on its chest.  This is a fair sized bird, but is quite shy compared to its cousin, the Northern Mockingbird.  It is also a mimic of other birds' songs, but tend to repeat them only twice instead of multiple times like the mockingbirds.

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Second and third visits were made to the mist nets to collect more birds before the nets were taken down.  This brilliant red male Northern Cardinal still has a grip on the netting. Notice his substantial beak that he uses to easily crack open large seeds.  I once saw a female bring a live wasp to her nest.  She sat beside the nest and carefully crushed the wasp in her heavy beak until it was almost like paste before she fed it to one of her young.


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The primary wing feathers are checked for wear.  This can indicate whether the bird has molted recently or if it has been a while.
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The male Northern Cardinal is being checked for fat deposits.

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This bird-bander is also acting as her own "scribe", the person who records the data being collected.

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Here the bird-bander is applying a band with specially made pliers.  These pliers allow the band to be closed gently so it won't fall off, but and leaves the band loose enough to not to pinch the bird's leg.  These pliers are made to apply bands of different sizes for different species of birds.


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Because Northern Cardinals have such thick beaks, it can hurt if they bite a finger.  This bird-bander uses a pipe cleaner for the cardinal to bite on while it is being examined and banded.  This female Northern Cardinal did not want to give up her "pacifier" when it was time to be released.


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The following photos are from March 8th, 2014, and are organized by the different data being collected.
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Three bird-banders with their empty bird sacks are
off to check the mist nets.  The nets were checked every thirty minutes to reduce the time any one bird would be tangled in a net.
 
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The first step is to locate a netted bird and carefully remove it from the fine netting.  Mist nets are designed so that when a bird flies into it and falls downward a pouch or pocket forms to safely contain the bird until a bird-bander arrives (mist net construction). The bird is then placed in a bag made of soft fabric that closes with a draw string.  This bag helps keep the bird calm and safe as other birds in the nets are removed.  This is a Northern Mockingbird being removed from a mist net.  Notice that this bird is a "recaptured" bird as it already has a leg band.  Data from this bird will be documented, too.
 
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Back at the banding station is a portable table covered with the needed equipment, reference books, data log sheets, etc.  In the toolkit there are several small canisters that each hold leg bands of a different size.  The bands are closed to form a complete circle and are strung on a thin wire.  Each band is stamped with a nine digit number plus the web address and phone number where one would report the discovery of the bird wearing the band. 
Also in the toolkit are leg gauges for determining what size band to use for each bird, banding pliers made specifically for opening the band so it can be placed around the bird's leg and then for safely closing the band, wing rules for measuring the wing chord length, etc.  Also on the table are portable digital scales and containers to weigh the birds as well as empty bird bags for collecting netted birds.

 
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The data log sheet includes columns for the bander's intials, the scribe's initials (if a second person is recording the bird's data), the band number and size, species four letter code, age and how determined, sex of the bird and how determined, observation of secondary skull growth, extent of fat deposits, wing length, weight, date and time of capture, 
area of netting location where the bird was captured, as well as a few other items.


 
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A bird-bander prepares to use a leg gauge to determine which size leg band to select for this Song Sparrow.

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The leg band sizes start at 0 for the smallest and range upward to 9 for the largest.  The band size 1B was used with most of the small birds netted on this day.  This bird-bander prepares to slip the appropriate notch around this House Wren's leg to assure selecting a band that will not be tight on the bird's leg and not too loose that it would slide off.
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Two bird-banders prepare to select a band from the canisters of sized leg bands.
 

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A bird-bander reads the number off the leg band for the scribe to record on the data log sheet while the House Wren rests calmly in the banders hand.

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Carefully, the bander uses these specially made pliers to reclose the leg band around the House Wren's leg.  She checks to be sure the band slides freely on the bird's leg.
 
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This is a Field Sparrow having a leg band applied.

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The bander also checks for fat deposits.  By blowing on the
chest and belly feathers the bird's translucent skin can be examined.  Here you can see the yellowish fat deposit that has accumulated in the area of the "wishbone", one of the first places that fat is stored.
 
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The area under the wings is examined, as well.  You can see two streaks of yellow under the skin on this bird.  Birds that have access to plenty of food during the winter store more fat, and as a result, may start Spring migration earlier and reach their breeding grounds before birds that have had difficulty finding sufficient food.
 
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This is an interesting chart that shows in black the areas where fat deposits accumulate.  Each pair of diagrams are shown on either side of the number used to "score" the bander's observation of fat deposits.

  
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Prior to weighing the bird, the weighing container is placed on the portable digital scales and the scale is set to zero.  This Song Sparrow is being placed head first into the weighing  container where it will rest calmly for the few seconds it takes to get its weight. 


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This sparrow is being weighed in a "Hello Kitty" weighing  container.  Someone has a sense of humor.

 
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This wren is head first into a much smaller weighing container.  The banders are very agile in handling these small birds.
  
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Checking the wing feathers for wear and for how complete the most recent molt is.  Twice a year most birds change out all their feathers, but in a gradual process so that only a few feathers are lost at a time and new one grow in before the next ones are lost.
 
 
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The wing chord is measured with a wing rule.  This measurement is recorded in millimeters.
 
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Skulling is another task that the bird-banders perform.  The bander wets the top of the bird's head and separates the feathers to expose the skin covering the skull.  When a bird hatches the skull has just one layer and appears pink.  During the next few months a second layer of bone forms under the first in a particular pattern.  This is called ossification and can be used in determining if the bird is in its first year or a mature bird. The bander uses the chart in the following photo to grade the amount of secondary skull that has formed.

    
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The chart for scoring skull ossification is displayed below.  All of the birds netted were after hatch year birds and were coded as 6s.

 
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A bander holds a Northern Mockingbird as her scribe records data.  This bird was caught twice during the morning and is noted as a "recapture" because it had been banded earlier.  This mockingbird was caught in a net a second time during the morning event.  Interestingly, this bird had no fat deposits.  If it is like the one that hangs out around our house, it probably burns off any fat from chasing after all the other birds in the area!


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This House Wren has an uninvited passenger in the feathers behind its eye.

 
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A close-up of the area disclosed an embedded tick.

 
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Once the tick was removed, you know I had to hold it!

 
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The tick on its back.
 
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The tick is off and moving.  We released it some distance away from the banding area.
 
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A White-throated Sparrow ready to be released.  Notice its white throat patch and conical beak it uses to split open seeds.  It has yellow lores between the base of its beak and its eyes and dark brown and white striping on the crown of its head.

 
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A Song Sparrow is ready for release.  Notice its streaked chest and it conical beak used for cracking open seeds.



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A House Wren is ready for release.  Notice its thin and slightly decurved beak used for catching insects.  The parasitic tick has been removed.



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A Carolina Wren with its white eye stripe and rustier tone is ready for release.  Its beak is longer and a little more decurved than the House Wren's.

 
 
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A Yellow-rumped Warbler is ready for release.  Notice its thin sharp beak that it uses to catch insects.

 
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An added treat for the day on March 8th, 2014 was an American Bittern that is reported to have made its winter home at Prairie Ridge EcoStation in November 2013.  We watched it for some time stalking around the edge of one of the ponds.  I have seen only one other bittern and that was over 30 years ago at Pine Island near Duck, NC on the Outer Banks.        (another local birder finds the bittern) 








 







My thanks go to all the bird-banders who graciously allowed me to photograph their work.  A special thank you to Keith Jensen and John Gerwin for including me in the 2014 event.








 



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