Migration Research Foundation - McGill Bird Observatory - Photo Library

McGILL BIRD OBSERVATORY

PHOTO LIBRARY

Fox Sparrow / Bruant fauve (Passerella iliaca)

NOTE: This species account has been moved to Piranga to allow for improved comparison among examples.
The updated profile is located at: http://www.natureinstruct.org/piranga/view.php/Canada/3A7B1F59DE8F597D

Introductory notes:
A rather tricky species to age by plumage, since age-related differences in wing and tail patterns are often subtle. Until late fall, most can be aged by skull development, but in spring many cannot be reliably classified beyond AHY. Sex can generally be determined only in the hand, by brood patch / cloacal protuberance during the breeding season, or by particularly short or long wing chords (<83 mm = female, >89 mm = male for the eastern race).

QUICK TIPS:

1) Look at the tail - outer rectrices are typically narrow and pointed on HY/SY, while broad and more rounded outer rectrices are typical of AHY/ASY, but beware that some individuals may replace their tail early, so this is less reliable for AHY/ASY

2) Check the outer primary coverts - they are relatively narrow and pointed with minimal pale brown edging on HY/SY birds, and relatively broad and rounded with distinct rufous edging on AHY/ASY birds

Species account updated April 2011

Ageing and sexing guidelines:

January - July:

ASY - U Broad and rounded primary coverts, broad rusty edging to greater coverts, broad and fairly truncate rectrices.
SY - U Relatively narrow primary coverts, limited rusty edging to greater coverts, narrow and tapered rectrices.

July - December:

AHY - U Broad and rounded primary coverts, broad rusty edging to greater coverts, broad and fairly truncate rectrices.
HY - U Relatively narrow primary coverts, limited rusty edging to greater coverts, narrow and tapered rectrices.

Ageing and sexing details:

JAN - JUL: after-second-year unknown

Body plumage provides no useful information about sex, which can be determined only during the breeding season by brood patch or cloacal protuberance. Eastern ASY birds may have a more richly rusty brown appearance than SY birds, on average, but this is not reliable - wing and tail should be evaluted to determine age.

Photo by Marcel Gahbauer, McGill Bird Observatory (QC), April 2006

ASY Fox Sparrows have relatively broad primary coverts typically showing some brown edging, but this can be variable and especially in spring may not be reliably distinct from SY individuals. ASY individuals also have wings that are somewhat more uniform in appearance, but this too can be a subtle difference from SY birds, and some intermediates are better left as AHY in spring.

An eastern Fox Sparrow showing broad primary coverts with little edging, but a relatively
uniform appearance to the wing overall.
Photo by Marcel Gahbauer, McGill Bird Observatory (QC), April 2006

A western Fox Sparrow, with no apparent edging to the primary coverts, but again with
a very uniform appearance to the wing overall.
Photo by Peter Pyle, Big Sur Ornithology Lab (CA), April 2007

Rectrices are broad and fairly truncate on ASY birds.

Photo by Marcel Gahbauer, McGill Bird Observatory (QC), April 2006

RETURN TO AGE/SEX OVERVIEW

JAN - JUL: second-year unknown

Body plumage provides no useful information about sex, which can be determined only during the breeding season by brood patch or cloacal protuberance. Eastern SY birds may have a somewhat less rusty brown appearance than ASY birds, on average, but this is not reliable - wing and tail should be evaluted to determine age.

Photo by Marcel Gahbauer, McGill Bird Observatory (QC), April 2006

SY birds have narrower and more pointed primary coverts, generally lacking edging, and there is usually at least a slight contrast between the fresher greater coverts and the juvenile feathers comprising the remainder of the wing.

A typical SY wing, with narrow and pointed primary coverts, and a uniform block formed by
the primary coverts, primaries, and secondaries, contrasting with the fresher greater coverts.
Photo by Marie-Anne Hudson, McGill Bird Observatory (QC), April 2008

Another example, where the shape of the primary coverts is more intermediate, and the
overall condition of the wing is suggestive of a SY individual, but far from conclusive;
this individual was identified as SY on the basis of its distinctly juvenile tail, but
considering the wing alone would be best classified as AHY.
Photo by Marcel Gahbauer, McGill Bird Observatory (QC), April 2006

SY birds have narrow and tapered rectrices, usually appearing more worn than those of ASY birds.

A distinctly SY tail, with narrow, pointed, and worn rectrices. This photo corresponds to the
indistinct wing in the previous section.
Photo by Marcel Gahbauer, McGill Bird Observatory (QC), April 2006

RETURN TO AGE/SEX OVERVIEW

after-hatch-year unknown

Body plumage provides no useful information about sex, which can be determined only during the breeding season by brood patch or cloacal protuberance. Eastern AHY birds may have a more rusty brown appearance than HY birds, on average, but this is not reliable - wing and tail should be evaluted to determine age.

Photo by Marcel Gahbauer, McGill Bird Observatory (QC), October 2005

Photo by Marcel Gahbauer, McGill Bird Observatory (QC), October 2009

ASY Fox Sparrows have relatively broad primary coverts, usually with some edging, and the wing has a relatively uniform appearance, including a fair bit of rusty edging on the primaries and secondaries.

Photo by Marcel Gahbauer, McGill Bird Observatory (QC), October 2005

Rectrices are broad and fairly truncate on ASY birds.

Photo by Marcel Gahbauer, McGill Bird Observatory (QC), October 2005

Photo by Marcel Gahbauer, McGill Bird Observatory (QC), October 2009

RETURN TO AGE/SEX OVERVIEW

hatch-year unknown

HY birds may on average have a less rusty brown appearance than AHY birds, but this is not reliable - wing and tail should be evaluated to determine age. Sex cannot be determined for HY birds.

A typical HY eastern Fox Sparrow.
Photo by Marie-Anne Hudson, McGill Bird Observatory (QC), October 2007

Photo by Marcel Gahbauer, McGill Bird Observatory (QC), October 2009

An Alberta bird; note the darker spots over most of the underparts, contrasting with the
more rusty spots on the throat and upper breast.
Photo by Marcel Gahbauer, Inglewood Bird Sanctuary (AB), September 2007

HY birds have narrower primary coverts with limited edging. The greater coverts, primaries, and secondaries all tend to have less rusty edging than on AHY birds, though the extent is variable.

A typical HY Fox Sparrow, with somewhat narrow primary coverts, and somewhat less
rusty edging across most of the wing than on AHY individuals.
Photo by Marcel Gahbauer, McGill Bird Observatory (QC), October 2009

A particularly dull individual, with minimal rusty edging anywhere on the wing.
Photo by Marcel Gahbauer, McGill Bird Observatory (QC), October 2005

An Alberta bird, somewhat darker on the wing overall.
Photo by Marcel Gahbauer, Inglewood Bird Sanctuary (AB), September 2007

HY birds tend to have relatively narrow and tapered rectrices, although there are some intermediates to beware of.

An intermediate example, which would require examination of the wing or skull
ossification to be confident about age.
Photo by Marie-Anne Hudson, McGill Bird Observatory (QC), October 2007

A somewhat more typically tapered HY tail, although a bit difficult to see in this pose.
Photo by Marcel Gahbauer, McGill Bird Observatory (QC), October 2005

RETURN TO AGE/SEX OVERVIEW