Tail Banding and Ageing Adult Red-tailed Hawks?

17 October 2015

Now that it is Red-tail time at most migration sites across North America, I wanted to remind birders and banders that you should never age adult Red-tailed Hawks specifically as 2nd-year or older by the presence or absence of tail banding? I was asked this question recently as it came up in discussion at the Goshute Mountains when someone referenced ageing Red-tailed Hawks as SY (2nd-year) by the presence of multiple tail bands, or ASY (after 2nd-year) by the absence of tail bands. Let me clarify that a 2nd-year Red-tail is one in its first adult plumage, meaning it was a juvenile (1st-year bird) last year. The truth is that tail patterns of adult Red-tails of every age vary from being completely banded to unbanded in no predominance. The only accurate way to age adult Red-tailed Hawks to a specific year is to determine if there is one generation or two generations of flight feathers (tail and wings). Body feathers may be helpful but it is often difficult to determine if old (from the previous molt) body feathers are 1st-year or adult feathers.

If there is one generation of flight feathers, the bird is AHY (fall) or ASY (after January 1). One generation of flight feathers occurs on adult Red-tailed Hawks in their first adult plumage at times, but almost never on older birds. However, birds cannot be aged based on eye color or probability, so AHY or ASY are the only options for birds with one generation of feathers. Adult Red-tailed Hawks with 2 generations of flight feathers where the older retained feathers are 1st-year feathers are SY (2nd-year) in fall or TY (3rd-year) after January 1. Red-tailed Hawks with 2 generations of adult flight feathers are ASY (fall) or ATY (after January 1). Sometimes it is possible to age Red-tailed Hawks to 3rd or 4th-year in fall, but that is difficult without extensive practice, and inaccurate in certain cases because Red-tails older than 4 years old can show identical molt patterns to 3rd and 4th-year birds.

So, NEVER age adult Red-tailed Hawks to a specific year based on tail banding or tail pattern...look for retained juvenile feathers or more than one generation of adult feathers! Check out these Red-tails in their first adult plumage (labeled 2nd-year) that lack multiple tail bands, and these after-2nd-year birds with obvious tail bands as example to fall back on in cases of doubt...and thanks for reading.

 2nd-year
 
  2nd-year
 
  2nd-year
 
  2nd-year
 
  2nd-year
 
  2nd-year
 
  2nd-year
 
  2nd-year
 
 2nd-year
 
 After-2nd-year
 
 After-2nd-year
 
 At least 8 years old (known nester)
 
 After-2nd-year
 
 After-3rd-year (after January 1st)
 
 At least 12 years old (known nester)
 
 At least 11 years old (known nester)
 
 At least 6 years old (known nester)
 
 After-2nd-year
 
 After-2nd-year
 
 After-2nd-year
 
 After-2nd-year
 
 After-2nd-year
 
 After-2nd-year
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