InfluentialPoints.com
Biology, images, analysis, design...
Aphids Find them How to ID Predators
"It has long been an axiom of mine that the little things are infinitely the most important" (Sherlock Holmes)

 

 

Generalized Aphid Predator (Passeriformes : Parulidae)

Setophaga coronata

Yellow-rumped Warbler

On this page: Identification & Distribution  Biology & Ecology  Biological Control of Aphids:  Predation of poplar aphids,  other aphids 

Identification & Distribution

The adult male yellow-rumped warbler (Setophaga coronata, see first picture below) in summer has a streaked back of black on slate blue, white wing patches, a streaked breast and conspicuous yellow patches on the crown, flank and rump. Females (see second picture below) in summer have streaked backs of black on blue-green and similar conspicuous yellow patches. There are marked differences between the subspecies: Male myrtle warblers (Setophaga coronata subspecies coronata) have a white throat and eye stripe, and a contrasting black cheek patch, whilst male Audubon's warbler (subspecies auduboni) have an additional yellow throat patch. Goldman's warbler (ssp. goldmani) is similar to Audubon's warbler, but has a white lower border to the yellow throat and otherwise darker plumage; in males the back is black. The black-fronted warbler (subspecies nigrifons) has a black head and front.

First image copyright Russ under a Creative Commons Attribution 2.0 Generic Licence 
Second image copyright tgreyfox under a Creative Commons Attribution -ShareAlike 2.0 Generic Licence 

Yellow-rumped Warblers are opportunistic foraging generalists. They are mainly insectivorous in summer, eating a variety of insects, but are especially known for eating insect species undergoing population irruptions, such as spruce budworm and various aphid species. On migration and in winter yellow-rumped Warblers also eat fruits, including bayberry and wax myrtle, and wild seeds. On their wintering grounds in Mexico they've been seen sipping aphid honeydew, as well no doubt as consuming the honeydew producers. The eastern subspecies of the yellow-rumped warbler (the myrtle warbler, Setophaga coronata coronata) breeds in summer in much of Canada and the northeastern USA, migrating to the southeastern USA, Central America and the Caribbean for overwintering. The western subspecies (Setophaga coronata coronata, Audubon's warbler) breeds in western Canada, the western USA and into Mexico, overwintering from the south western USA to Central America. Goldman's yellow-rumped warbler (Setophaga coronata goldmani) is a non-migratory endemic in the highlands of Guatemala, and the black-fronted warbler (Setophaga coronata nigrifons) is a non-migratory endemic in Mexico.

 

Biological Control of Aphids

Predation of poplar aphids

Aphid predation by birds is under-recorded, partly owing to the difficulty of visually identifying their prey to be an aphid, but also because soft-bodied insects may disintegrate in crop contents (obtained by using purgative or neckband methods often used in bird feeding behaviour studies). However, Eugene Beckes  did manage to photograph this yellow-rumped warbler eating aphids which were feeding on leaf petioles of what appears to be an eastern cottonwood tree (Populus deltoides).

image copyright Eugene Beckes under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Generic Licence 

Eugene's photograph is good enough to attempt a visual prey identification - the aphids are a Chaitophorus  species, most likely Chaitophorus populicola. This aphid sometimes attains pest status in plantations of eastern cottonwood (Coleman & Jones, 1988 ). Most of the aphids are pale, which suggests we may be looking at the large pale oviparae of Chaitophorus populicola which are found in October (photo taken on October 14, 2013). Alternatively the aphids could be another related species, the yellowish Chaitophorus populifolii, but this is normally a leaf-surface feeder.

Predation of other aphid species

Terrill & Ohmart (1984)   examined the prey selection of yellow-rumped warblers in relation to resource abundance in three sites in Arizona. Prey selection was assessed by dissection of stomach contents of a sample of birds, and resource abundance was assessed by sweep-net samples. At one site (Santa Maria), aphids made up 88% (numerically) of the sweep net sample, and comprised 46.5% (by volume) of the stomach contents. At the other sites chironomids or cicadellids were most abundant, and these were then the favoured prey. Yarbrough & Johnston (1965)   also noted that on occasions yellow-rumped warblers ate considerable numbers of Homoptera, chiefly aphids.

A video of a yellow rumped warbler eating aphids  on house plants, posted on youtube by Cole, shows the foraging strategy of the yellow-rumped warbler. They mostly glean insects from the vegetation, but may also pursue their prey in short spurts of flight. Colette Micallef also posted a video showing a yellow-rumped (Audubon's) warbler  feeding on insects (almost certainly aphids) on 23 April 2016 in Colorado, USA.

A pristine male yellow rumped warbler  was one of several birds seen eating aphids on rose bushes in a backyard by members of the Southwestern New Mexico Audubon Society on April 15, 2009. The most likely prey species is the common rose aphid Macrosiphum rosae  which has a cosmopolitan distribution. Other bird species have been reported feeding on rose aphids - including the blue tit  in Europe.

Bob Armstrong photographed a yellow rumped warbler eating aphids  from a heavily infested unidentified flowering shrub in Alaska. Jim Edlhuber observed the first yellow rumped warblers  of the season at the Fox River Sanctuary in Waukesha, Wisconsin, USA, on 8 April 2014. There were 3 present and they were hopping around in the trees eating what appeared to be small insects - again most likely aphids.

Acknowledgements

For bird identification we have used Cornell Lab of Ornithology   for the key characteristics, together with the latest Wikipedia account for each species.

For aphids we have made provisional identifications from high resolution photos of living specimens, along with host plant identity. We have used the keys and species accounts of Blackman & Eastop (1994)  and Blackman & Eastop (2006)  supplemented with Blackman (1974) , Stroyan (1977) , Stroyan (1984) , Blackman & Eastop (1984) , Heie (1980-1995) , Dixon & Thieme (2007)  and Blackman (2010) . We fully acknowledge these authors as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure  provided by Blackman & Eastop (2006).

Useful weblinks 

References

  • Coleman, J.S. & Jones, C.G. (1988). Acute ozone stress on eastern cottonwood (Populus deltoides Bartr.) and the pest potential of the aphid Chaitophorus populicola Thomas. Environmental Entomology 17, 207-212.  Abstract 

  • Terrill, S.B. & Ohmart, R.D. (1984). Facultative extension of fall migration by Yellow-Rumped Warblers (Dendroica coronata). The Auk 101(3), 427-438.  Full text 

  • Yarbrough, C.G. & Johnston, D.W. (1965). Lipid deposition in wintering and premigratory Myrtle Warblers. The Wilson Bulletin 77(2), 175-191.  Full text