Who?
WHO ARE THESE CRANES?
MEASUREMENTS
Identification of subspecies of sandhill cranes requires the determination of gender which can not be ascertained from a physical
examination. We hope that blood analyses will determine gender. Measurements used for comparison of subspecies are from two
sources: Johnson and Stewart (1973) and Schmidt and Hale (1997). However, the birds reported in these studies were from the
Mid-Continent Population (Central Flyway - - the migration corridor between the Rocky Mountains and Mississippi River), and
those
in the Pacific Flyway (west of the Rockies) may differ morphologically. Measurements were plotted on charts for comparisons.
Tarsus
The tarsus is the long bone in the lower leg.
Length of tarsus (n = 7) measurements were
generally shorter than Canadian sandhill cranes,
and mostly within the upper limits for lessers.
Wing Chord
Wing chord is measured from the bend of the
wing to the tip. Measurements (n = 8)
overlapped with all 3 subspecies, but 4 of 8
birds were within the standard deviation for
Canadians. One crane measured larger than any
Canadians reported, but within the range for
Greaters. The other 3 cranes were closest to
means for lessers.
Exposed Culmen
This measurement is from the base of the
upper mandible to the tip. Four exposed
culmen measurements (n = 8) were closest
to the ranges reported for Canadian sandhill
cranes, while the other four fell between the ranges for Canadians and lessers.
Weight
Weights of cranes (n = 7) fell within the ranges
for greater and Canadian sandhill cranes, with
little overlap with reported weights of lessers.
Most weights were closest to the means for
Canadians, however, weights of two birds were
closer to greaters.
Middle Toe
Measurements of the middle toe fell mostly
within the upper ranges of lesser sandhill
cranes with some overlap with female
Canadians.
SUBSPECIES DETERMINATION
We believe that the cranes in this study were Canadian sandhill cranes. Most of their measurements were within the ranges reported
for this subspecies. Disparities in some measurements may indicate that there are morphological differences between cranes of the
Central Flyway and those of the Pacific Flyway. The fact that these cranes migrated to the
B.C. and southern Alaska
coasts also supports the conclusion that they are Canadians. According to the book The Birds of British Columbia (Campbell et al.
1990), about 1,500 Canadian sandhill cranes nest along the B.C. coast.
For the birds we captured , the head profiles seemed to match those of Canadians, with a flat forehead and medium bill (see photos of
birds on the other pages). Lessers have a rounded head and fine, short bill, while
Greaters also have a flattened forehead, but a longer
bill. We also noted that the legs were shorter than greaters that we had previously handled. The heads of these birds appeared
different than lesser sandhill cranes we have observed in California, and eastern Oregon and Washington, and their bills appeared
shorter than typical greaters.
References
Campbell, R. W., N. K. Dawe, E. McTaggart-Cowan, J. M. Cooper, G. W. Kaiser, and M. C. E. McNall. 1990. The birds of British Columbia. Royal
British Columbia Museum, Victoria, B.C.
Johnson, D. H., and R. E. Stewart. 1973. Racial composition of migrant populations of Sandhill Cranes in the northern plain states. Wilson Bulletin
85:148-162.
Schmidt, G. C., and B. Hale. 1997. Sandhill Crane hunts in the Rio Grande Valley and southwest New Mexico. Proceedings North American Crane
Workshop 7:219-231.
Click the following items to see detailed results for this study: