McGILL BIRD OBSERVATORY

PHOTO LIBRARY

Tree Swallow / Hirondelle bicolore (Tachycineta bicolor)

 Seasonal status at MBO:

JAN
       
FEB
       
MAR
       
APR
       
MAY
       
JUN
       
JUL
       
AUG
       
SEP
       
OCT
       
NOV
       
DEC
       
  common
  fairly common
  uncommon
  rare
  occasional
  no records
 
QUICK TIPS:  (applicable only in spring/summer)
1) Consider the body plumage:
     -
if there is any brown on the head or back in spring/summer the bird is a female
          - >50% brown indicates a SY female
          - 10-50% brown indicates an AHY female (zone of overlap in plumage between SY and ASY)
          - 1-10% brown indicates an ASY female
     - if the head and back are entirely green-blue it may be a male of any age or an ASY female

2) Check the flattened wing chord - if it is <114 mm the bird is a female, if it is >121 mm the bird is a male

Note: the above tips are based on the long-term research of Dr. David Hussell at Long Point Bird Observatory

Species account updated April 2009

Ageing and sexing overview:

January - July:

AHY - M
Upperparts entirely blue-green; sex must be confirmed by cloacal protuberance.
ASY - F
Upperparts almost completely to entirely blue-green; sex must be confirmed by brood patch.
AHY - F
Upperparts 50-90% blue-green.
SY - F
Upperparts over 50% brown.

-

June - December:

AHY - M
 
     
AHY - F
 
     
HY - M
 
     
HY - F
 
     
JUV - U
 
 

Ageing and sexing details:

after-hatch-year male

In spring, male Tree Swallows of all ages are entirely blue-green above.  Unless there is abnormal retention of brown juvenile feathers, age cannot be determined.  Some males can be sexed if they have a sufficiently long flattened wing chord (at least 121 mm).  Otherwise, sex can be reliably assessed only through the presence of a cloacal protuberance, as ASY females can also be entirely blue-green above.


Photo by Marcel Gahbauer, April 2006
 


Wings are uniform in colour, with a blue-green sheen to the coverts and tertials.


Photo by Marcel Gahbauer, May 2006


The blue-green upperparts extend through to the rump, and there is often a blue-green tinge to the rectrices.


Photo by Marcel Gahbauer, May 2006

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after-second-year female

In spring, ASY female Tree Swallows are 90-99% blue-green on their upperparts, and can be virtually indistinguishable from males.  Some females can be sexed reliably by wing chord, if it is 114 mm or shorter.  Otherwise, any Tree Swallows with this colouration must be sexed as females only if they have a brood patch.


Photo by Marcel Gahbauer, April 2006
 


Wings are uniform in colour, with a blue-green sheen to the coverts and tertials.


Photo by Marie-Anne Hudson, May 2008
 


The blue-green upperparts extend through to the rump, and there is often a blue-green tinge to the rectrices.


Photo by Marie-Anne Hudson, May 2008

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after-hatch-year female

Some female Tree Swallows have more (>50%) blue-green on the upperparts than is typical of SY birds, and less (<90%) than definite ASY females.  They can be recognized as females by having at least 10% brown feathers, especially on the forehead, and sex can be confirmed by brood patch, but age cannot be determined with accuracy.


Photo by Marcel Gahbauer, April 2006


Wings may have a blue-green sheen in places, or may be largely brown.


Photo by Marcel Gahbauer, April 2006
 


The blue-green upperparts eusually xtend through to the rump, and there is often a blue-green tinge to the rectrices.


Photo by Marcel Gahbauer, April 2006

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second-year female

Primarily brown above, with dull blue-green flecks covering up to 50% of the upperparts; the amount of blue-green on the head may be quite variable, as shown by the photos below.


Photo by Marcel Gahbauer, June 2006


Photo by Marcel Gahbauer, April 2006


Photo by Marie-Anne Hudson, May 2007

 


The wing is mostly brown, though on some individuals there may be some feathers, especially toward the back, that have a fair amount of blue-green gloss.


Photo by Marcel Gahbauer, June 2006


Photo by Marie-Anne Hudson, May 2007

 


Tail mostly brown, sometimes with a faint blue-green tinges to the rectrices.


Photo by Marie-Anne Hudson, May 2007


Photo by Marcel Gahbauer, June 2006

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after-hatch-year male

 



 




 



 

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after-hatch-year female

 


 
 




 



 

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hatch-year male

 



 




 



 

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hatch-year female

 



 


 



 



 

juvenile unknown

Juvenile Tree Swallows are brown below and white above.  This individual was photographed around 15 days of age, a few days prior to fledging.


Photo by Marcel Gahbauer, Hamilton (ON), June 2006
 


Wings are uniformly gray-brown.


Photo by Marcel Gahbauer, Hamilton (ON), June 2006
 


The tail is uniformly gray-brown, and at age 15 days is still in the process of growing in.


Photo by Marcel Gahbauer, Hamilton (ON), June 2006

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2002- The Migration Research Foundation Inc.