BCHU Sugar Water Consumption Rates

The abstract below was presented at the 6th International Hummingbird Banding Workshop held at Dan Brown’s “Hummer House” ranch near Christoval, TX, during 2005.

Black-chinned Hummingbird Sugar Water Consumption Rates at 4 Ranches in the Edward’s Plateau Ecoregion in Texas during 2005.

Brent Ortego¹ and Ross Dawkins²

¹Texas Parks and Wildlife Department, 2805 N. Navarro, Suite 600B, Victoria, TX 77901

²Chemistry Department, Angelo State University, Box 10892, San Angelo, TX 76909

Black-chinned Hummingbird (BCHU) (Archilochus alexandri) sugar water consumption were studied at 4 rural ranch banding sites in the Edward’s Plateau during the 2005 breeding season. Dan Brown Ranch, Tom Green County, was located at the edge of the S. Concho River floodplain in the western Edward’s Plateau in a deciduous park-like yard with 19+ 48-oz hummingbird feeders. Due to livestock grazing and high white-tailed deer (Odocoileus virginiana) densities there were few hummingbird nectar producing plants. In the southeastern Edward’s Plateau, Bob and Sudie Burditt Ranch, Real County, was at the edge of the Frio River floodplain with park-like deciduous yard with 12 96-oz hummingbird feeders. Few hummingbird nectar producing plants were present for the same reasons as the Brown Ranch. Annie and Corky Matter Ranch, Kendall County, was on the top of a hill about ½ mile (.8 km) from a very small Flat Rock Creek in a cedar/hardwood savannah with 10 quart hummingbird feeders. Numerous hummingbird nectar plants were available in the residential yard of the banding site, but not in the rest of the ranch because of livestock and deer grazing. Egon and Sue Wiedenfeld Ranch, Kendall County, was at the edge of the floodplain of Big Joshua Creek in a park-like hardwood setting. Many hummingbird nectar plants were available in the 10-acre (4 ha) residential yard as well as regular occurrence in the surrounding pastures because of lower livestock and deer numbers.

At the Burditt, Matter and Wiedenfeld Ranches 1270 BCHU were captured during visits once per month from April through June using modified Russell traps, and sugar water consumption was recorded daily and summed weekly. Banding was discontinued after June because of the beginning of migration. The Lincoln’s Index was used to calculate hummingbird densities in May and June (69 recaptures from birds previously banded) and compared to sugar water consumption for the week of the banding. Sugar to water ratios of 1:4 was used at 2 ranches, and 1:5 and 1:3 at other ranches. All sugar water consumption was converted to 1:4 equivalents because this is the rate used at most hummingbird feeders.

Sugar water consumption at each ranch is graphed below in gallons consumed per week. Pattern of sugar water use at each ranch is fairly similar, but consumption rate varied by ranch.

Fig. 1 Gallons of sugar water consumed per week at 4 ranches in the Edward’s Plateau, TX, during 2005.

BCHU estimates per site varied from a low of 1542 at the Matter Ranch to 3000 at the Brown Ranch. Highest consumption rate by hummingbird was at the Brown and Burditt ranches with the lowest availability of hummingbird nectar producing plants.

Table 1. Sugar Water Consumption and the Lincoln’s Index BCHU Estimated Population.

SITE	LINCOLN’S INDEX	HUMMERS/GALLON
Brown 1999	3000	1000/gal
Burditt 2005	2251	855/gal
Wiedenfeld 2005	2016	1275/gal
Matter 2005	1542	1610/gal

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