Mallard Anas platyrhychos Linnaeus       Field Guide IDs: NG-76; G-46; P-48; PW-pl 14; AE-pl 107; AW-pl 97; AM (I)- 158 Nest Location Nest Type Eggs & Mating System Dev. & Parental Care Primary & 2ndary Diet.. Foraging Strategy F I: 28(26-30) DAYS PRECOCIAL 2 F 7-10 (6-15) MONOG F: 42-60 DAYS F GREENS AQUATIC INVERTS INSECTS BREEDING: Shallow pond, lake, marsh, flooded field. 1 brood. DISPLAYS: See: Duck Displays. NEST: Usu near water; of cattails, reeds, grass, concealed by vegetation. Occ in hollow logs, abandoned nests, at tree base, human-made structure, etc. Down-lined as clutch is completed. EGGS: Greenish-buff/grayish-buff/whitish. 2.3 (58 mm). DIET: Seeds and shoots of sedge, grass, and aquatic veg, grain, acorns; insects, aquatic invertebrates. Laying females may eat 2x more animal food than males or nonlaying females. CONSERVATION: Winters s to c Mexico. Often poisoned by lead pellets; alkaline-poisoned in w by foraging in ephemerally damp lake beds. NOTES: Seasonally monogamous, switching mates each year. Male territorial defense centered on female. Male deserts after first week of incubation to join male flocks. Nest predation increases as vegetation height decreases. During molt, female flightless 32 days, male 34; decrease flight muscles, increase leg muscles and layer of insulating fat. Analysis of trace elements (especially metals) in flight feathers can identity geographic origin. STANFORD. NOTES: Common winter resident at Lagunita, usually seen foraging in shallows at the edge of the lake. Several pairs remain to breed in spring; this is the most common breeding waterbird on campus. During winter and spring, small numbers occasionally occur in the small Arboretum pond and the wetland area south of Campus Drive between Lomita Drive and Palm Drive. ESSAYS: Parasitized Ducks; Vocal Development; Bird Voices; Metallic Poisons; Dabblers vs. Divers; Molting; Flamingo Feeding. REFERENCES: Bellrose, 1976; Bossema and Roemers, 1985; Gooders and Boyer, 1986; Swanson, et al. 1985.