Wilson's Warbler

Wilsonia pusilla Wilson

 

 

 

Field Guide IDs:
NG-384; G-292; PE-242; PW-pl 51; AE-pl 358; AW-pl 409; AM(III)-180


Nest
Location
Nest
Type
Eggs &
Mating System
Dev. &
Parental Care
Primary &
2ndary Diet
..
Foraging
Strategy
F
I: 10-13 DAYS
ALTRICIAL
VINE
.........TANGLE
0 - 3 feet
F
4-6 (2-7)
MONOG
(POLYGYN)
F: 8-11 DAYS
MF

HOVER &
.........GLEAN
HAWKS
BARK..
....GLEAN

BREEDING:

Thickets and brush in well-watered locations (esp willow and alder bogs), riparian woodland. 1 brood.

DISPLAYS:

?

NEST:

Variably placed: high-elevation nests are smaller and built on ground; coastal nests larger and above ground. Bulky, esp for such a small bird; of dead leaves, grass, moss, lined with fine grass, occ hair. Built in 5 days.

EGGS:

White to creamy, marked with browns, variable, often wreathed. 0.6" (16 mm).

DIET:

Also occ berries.

CONSERVATION:

Winters s to w Panama. Uncommon cowbird host.

NOTES:

Breeds over a wide range of elevations: coastal populations have smaller clutches, lower nesting success, and are monogamous; high-elevation populations have larger clutches, higher nesting success, and polygyny occurs regularly. Females brood. Much more common in w than in e.

STANFORD. NOTES:

Uncommon to fairly common migrant and summer resident in woodland and scrub near the Dish, with a few pairs probably nesting there. Uncommon migrant elsewhere on campus.

ESSAYS:

Polygyny; Monogamy; Average Clutch Size; Variation in Clutch Sizes.

REFERENCES:

Stewart et al., 1977.

Except for Stanford Notes, the material in this species treatment is taken, with permission, from The Birder's Handbook (Paul Ehrlich, David Dobkin, & Darryl Wheye, Simon & Schuster, NY. 1988).