Tom, et al.

In addition to Mark Hoffman's two references ... here's more than you 
(n)ever (!) wanted to know on the subject ... Taken from the Townsend's 
Warbler Birds of North America (BNA) on-line account.

Phil


FOOD HABITS

FEEDING
Main foods taken
         Few quantitative analyses. Insects. Honeydew excreted by scale 
insects in low-latitude cloud forests (Greenberg et al. 1993).

Microhabitat for foraging
         Little known. During breeding season, feeds primarily in upper 
third of coniferous canopy (Bent 1953, Marzluff and Lyon 1983). In ne. 
Oregon, prefers foraging in grand fir (Mannan and Meslow 1984). 
Occasionally forages in deciduous understory trees, especially just before 
migration (Bent 1953, Gabrielson and Lincoln 1959). In s.-central Alaska, 
breeding adults prefer to forage in medium-diameter white spruce (18–38 cm 
diameter at breast height [dbh]) before young hatch, but subsequently 
forage in deciduous and coniferous substrates while provisioning nestlings 
and newly fledged young (Matsuoka et al. 1997b).

         Strata and substrate used for feeding vary with area during 
migration and winter. Mean foraging height of wintering individuals in 
Chiapas cloud forest was 6.9 m ± 3.7 SD (n = 327; Vidal-Rodriguez 1992). 
Patches of honeydew-producing scale insects are used regardless of height 
(Greenberg et al. 1993). Patches occur on outer branches of live oaks 
(Quercus rugosa, Q. laurina, and Q. crassifolia) and nearby saplings. In 
Costa Rica, foraged from ground to 20 m, most commonly 0.5–4.0 m (Tramer 
and Kemp 1980).

Food capture and consumption
         Few quantitative analyses. Diurnal forager. Typically gleans 
insects from clumps of conifer foliage and leaf surfaces of deciduous 
plants during breeding season (Bent 1953, Dobkin 1994, SMM). Occasionally 
takes flying insects in air (hawking; Dobkin 1994). In Costa Rica at 
Monteverde (Tramer and Kemp 1980), most flexible among migrant warblers in 
feeding method: gleaning (51%) is the most common method, followed by 
hawking (38%), hovering (9%), and flower-feeding (2%; n = 39). Average 
foraging speed 0.16 m/s ± 0.13 SD (n = 40). Feeds on honeydew secreted at 
the tip of threadlike anal tube of scale insects, commonly breaking tube 
(Greenberg et al. 1993).

DIET
         Little information. Western spruce budworm (Tortricidae) important 
where present (Langelier and Garton 1986). Feeds on caterpillars, moths, 
winged insects, and other invertebrates commonly found on coniferous and 
deciduous foliage (Gabrielson and Lincoln 1959, SMM). In California 
Oct–Jan, 31 specimens contained 95% animal matter (Beal 1907). Of these 
animal parts, 42% were true bugs (Hemiptera, mostly stinkbugs 
[Pentatomidae]), 25% bees and ants (Hymenoptera), 21% beetles (Coleoptera, 
mostly snout beetles, or weevils [Curculionidae]), 12% other insects or 
spiders. Vegetable foods: seeds and leaf galls. Honeydew of scale insects 
important locally on winter range (Greenberg et al. 1993). In winter, 
visits feeding stations where cheese, marshmallows, and peanut butter are 
offered (Bent 1953).

FOOD SELECTION AND STORAGE
         No information.

NUTRITION AND ENERGETICS
         No information.

METABOLISM AND TEMPERATURE REGULATION
         No information.

DRINKING, PELLET-CASTING, AND DEFECATION
         No information.


CITATION:
Wright, A. L., G. D. Hayward, S. M. Matsouka, and P. H. Hayward. 1998. 
Townsend’s Warbler (Dendroica townsendi). In The Birds of North America, 
No. 333 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., 
Philadelphia, PA.



At 16:44 01/03/2006, Tom Marko wrote:
>Gail Mackiernan and Barry Cooper, Colesville, MD, write: "The warbler was
>actively gleaning along branches and even along the trunks of trees, a bit
>like a Black and White."
>
>I'm curious, what comprises the warbler's diet this time of the year?

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Phil Davis      Davidsonville, Maryland     USA
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