Egg characteristics and body reserves of neonate Ross' and lesser snow geese / Stuart M. Slattery and Ray T. Alisauskas.

Includes bibliographical references (pages 983-984).

We studied the effects of species, nesting chronology and egg size on composition
of eggs and goslings of Ross' (Chen rossil) and Lesser Snow Geese (Chen caerulescens).
Compared to early nesters, late-nesting Ross' Geese laid eggs with less yolk protein, which
in tum produced goslings with smaller pectoralis muscles. Larger pectoralis muscles of young
that hatch early may enhance thermogenesis when conditions are colder. Egg composition
varied isometrically with egg size. Con specifics from larger eggs were structurally smaller
for their egg size yet contained the same relative nutrient content as goslings from smaller
eggs; thus goslings from larger eggs had relatively more lipid reserve. Larger egg size may
give an initial energetic advantage to goslings during periods of nutritional or thermal stress.
Although no interspecific variation in egg composition was observed, Ross' Geese hatched
with more protein (scaled to egg size) and larger gizzards (scaled to body size). In addition,
Ross' Geese had less water per gram of dry skeletal tissue mass than did Snow Geese which
indicates greater functional maturity of Ross' Goose neonate tissue. Digestive efficiency,
thermoregulatory ability and locomotor capacity may be relatively better in Ross' Geese
than in Snow Geese and these characteristics may represent adaptations to metabolic constraints
associated with smaller neonate body size and forage requirements.