Final Report for FW08-312
Aleutian cackling geese (Branta hutchinsii leucopareia) stop in Humboldt County, California, and feed on private pasture lands during their yearly migration. Their expanding population has led to increased conflicts over forage consumption and, ultimately, available forage allocation for beef cattle on ranches in Humboldt County, California. A research project was developed to quantify Aleutian cackling goose forage consumption and effects on pasture production rates on three private beef ranches in Humboldt County. Data collection occurred during late winter 2008 and early spring 2009. Pasture production was estimated under conditions of no grazing, grazing by cattle only, and grazing by cattle and geese. The results of this study show that Aleutian cackling geese are having a statistically significant impact on pasture production.
Aleutian cackling geese (Branta hutchinsii leucopareia) use private pasture lands in Humboldt County, California, as a staging area on their migration from wintering grounds in California’s Central Valley to breeding grounds of the Aleutian Islands in Alaska. Aleutian cackling geese were listed as an endangered species in 1973 when less than 800 birds were recorded. Successful conservation measures allowed the population to expand, and they were delisted in 2001. The population estimate for 2005 was over 100,000 (USFWS 2008). Almost the entire population spring stages in the northern California coastal region (Bachman 2008).
Geese have selective feeding behaviors and prefer plants that have low fiber and high protein content (Riddington et al. 1997). This ratio is found more readily in newer plant growth (Langer 1973), which can be stimulated by maintaining forages at a short stubble (leaf) height. Rotational grazing practices are one way to keep short stubble heights. Many local ranchers adopted these practices within recent years for economic and ecological sustainability. This management practice has proved to be highly attractive to Aleutian cackling geese. As the population continues to increase, they exert increased grazing pressure on local private ranch lands. This pressure has created conflicts in forage utilization and the subsequent allocation of available forage to livestock production versus consumption by the geese.
This project was designed to address the economic impacts of Aleutian cackling goose grazing on three local beef ranches by providing an analysis of the forage partitioning between use by geese and that for beef production. Estimates of pasture production were calculated with the use of empirical data collected under 3 conditions: 1) with no grazing by cattle or Aleutian cackling geese, 2) with grazing by cattle only, and 3) with grazing by cattle and Aleutian cackling geese.
This project used three ranches, with four study pastures on each ranch. Two ranches are located in the Eel River delta area and one ranch is located in the Arcata bottomlands. One 3 meter x 3 meter ‘No-Grazing’ exclosure was set up in each study pasture during late November and early December 2008. This exclosure was partitioned into 1 meter x 1 meter plots that were sampled only once throughout the study. Sampling coincided with each producer’s grazing rotation schedule. Directly before cattle were rotated through study pastures, samples were taken from open areas of the pasture as well as from a plot inside the ‘No-Grazing’ exclosure. Once cattle were moved out of the study pastures, samples were again clipped from the open areas. After these samples were taken, three 1 meter x 1 meter ‘No Goose Grazing’ exclosures were set up in the study pastures to prevent grazing by geese. These remained in place in the study pastures until the next scheduled grazing rotation. Directly before the next rotation into the study pastures, samples were clipped from a ‘No-Grazing’ plot, the open pasture and also from the ‘No Goose Grazing’ exclosures. This process was repeated throughout the season while Aleutian geese were present in Humboldt County. All samples were hand clipped using a 0.96 ft2 sampling frame. Samples were bagged and dried at 65° C for a minimum of 48 hours, weighed in grams and then converted to pounds per acre. Results were compared to show pasture production with no grazing, and with and without grazing by cattle and Aleutian cackling geese.
The results of this study show that Aleutian cackling geese are having a statistically significant impact on pasture production. Forage losses in 2008-2009 were 270 lb/acre on the Hunt Ranch (Figure 1), 254 lb/a on the Russ Ranch North (Figure 2) and 723 lb/a on the Russ Ranch South (Figure 3). These results show that goose presence is a significant factor when pasture forage regrowth is measured.
- Pasture production with and without grazing on the Hunt Ranch in Humboldt County, California.
- Pasture production with and without grazing on the Russ Ranch North Unit in Humboldt County, California.
- Pasture Production with and without grazing on the Russ Ranch South Unit in Humboldt County, California.
Education and Outreach Outcomes
This study has the potential to support Humboldt County ranchers who practice intensive rotational grazing to seek compensation from the US FWS for lost forage.
Funding from University of California will allow continued studies of goose impacts on pasture production.
We recommend continued study of forage production, goose feeding habits and any other studies that would help to manage or resolve this conflict between agriculture and environmental interests.