Gunnison sage-grouse (Centrocercus minimus
, hereafter GUSG) is a species of concern in Colorado. Two conservation issues addressed in the Gunnison Sage-grouse Rangewide Plan (RCP) are the population persistence of GUSG (especially the small populations) and the relatively low genetic diversity among GUSG. Augmenting small GUSG populations is a potentially useful management tool to address these conservation concerns. Five alternative techniques to transplanting yearling or adult individuals are discussed in the RCP, including use of captive-reared GUSG. Researchers at the U.S.D.A. National Wildlife Research Center (NWRC) in Fort Collins, CO were able to maintain 18 yearling greater sage-grouse (C. urophasianus
, hereafter GRSG) in captivity for 8 months. Recent Colorado Parks and Wildlife (CPW) supported research on GRSG
with the University of Idaho has evaluated different aspects of captive-rearing techniques. The objectives for our GUSG project are to: 1) collect GUSG eggs from captive and wild females, 2) artificially incubate and hatch eggs, 3) develop captive breeding techniques for GUSG for all ages, 4) determine if captive GUSG can initiate incubation and rear a brood in captivity, 5) augment wild surrogate broods with domestically-reared chicks at 1-, 3-, 5-, and 7- weeks of age.
Female GUSG were captured using spot-lighting techniques in 2009-2011. Females were radio-marked and monitored to assist in locating nesting and brooding females. Eggs were collected from laying and incubating wild females. Eggs were transported from the Gunnison Basin to the CPW Foothills Wildlife Research Facility (FWRF) in Fort Collins and artificially incubated and hatched (figure 1
). When an internal or external pip was observed (25-26 days) eggs were moved to a hatcher (figure 2a
| a. |
| b. |
Juveniles (> 10 days of age) and the captive flock were housed at the NWRC aviaries (figure 2b)
. Husbandry techniques from egg collection and hatch to adulthood were developed cooperatively with CPW Veterinary and Avian Research Staff, NWRC Staff, and Avian Specialists at the Denver Zoo. In 2009, a captive-reared GUSG flock was established and maintained until fall-2011 for research purposes.
We collected 206 eggs over 3 years from incubating and laying GUSG females. We collected 137 eggs from wild laying and incubating females and 69 eggs from captive laying females. Our hatch success was 74%. Fifty-five eggs did not hatch and 35% of the unhatched eggs were infertile, resulting in 86% egg hatchability.
To assess augmentation success in 2010 and 2011, we radio-marked 86 (figure 3
)wild-reared day-old GUSG chicks and 74 captive-reared chicks that were augmented to wild GUSG broods.
We augmented broods with similar aged captive-reared chicks. Adoption success was good and captive-reared chick survival was low, but varied with chick age. Quantified survival estimates and adoption rates are pending complete data analyses, although progress reports in 2010
During captivity, chicks and juveniles were provided a diverse diet. We provided varying quantities of invertebrates (superworms, fruitflies, wax worms, mealworms, and house crickets) (Figure 4a
), forbs, commercial game bird chow, and vitamin supplemented water. Subadult and adult GUSG were provided naturally occurring forbs in the aviary, superworms, commercial game bird chow, sagebrush, and vitamin supplements water as part of year-round husbandry diet. Quantities of food items varied by bird/flock age and season of the year (Figure 4b, 4c, and 4d
Our largest cause of captive-chick mortalities were complications as a result of bacterial infections. Precautions were taken to improve cleanliness and isolation of cross-contamination during incubation, hatch and early-rearing through the course of our study. We were successful in reducing, but not eliminating, bacterial infections. We were also successful in controlling infections of West Nile Virus by holding birds in mosquito proof enclosures (Figure 4e
), conducting on site mosquito control, and managing the aviaries to limit mosquito activity (Figure 4f
We documented successful “lek” formation (Figure 5
)and breeding behavior in captivity. We controlled male-female access during the breeding season for approximately 14 days in April in 2010 and 2011. Captive females produced viable eggs and exhibited nesting behavior.
From September through November 2011, we transitioned the research project to a long-term captive-flock care and maintenance project at the CPW FWRF. On 23 November 2011, the captive GUSG were transported to the CPW FWRF from the NWRC and released into a newly constructed aviary.
In summary, we are the first to develop basic husbandry protocol of GUSG captive-rearing. We have developed the husbandry protocol for egg collection, storage, incubation and hatching. We have also developed chick, juvenile, subadult, and adult husbandry maintenance protocol. Additionally, we document that GUSG raised in captivity, can and will successfully breed, produce viable eggs, and with limited success, raise chicks in captivity.
Currently the project personnel are in the process of proofing and editing data and conducting analyses. A full project write-up will be completed by Spring 2013.
Period Covered: 1 March 2009 – November 2011
- Lief Wiechman, Colorado State University
- A.D. Apa, Ph.D., CPW
- M.P. Phillips Ph.D., CPW
- Alan B Franklin, Ph.D., NWRC/APHIS
- John V. Azua, Jr., Denver Zoo
All information in this report is preliminary and subject to further evaluation. Information MAY NOT BE PUBLISHED OR QUOTED without permission of the author. Manipulation of these data beyond that contained in this report is discouraged.
Demography and Dispersal
Principal Investigator: Michael L. Phillips
The U.S. Fish and Wildlife Service (USFWS) has determined that the Gunnison sage-grouse (Centrocercus minimus
) is a candidate species for listing as threatened or endangered under the Endangered Species Act. Seven Gunnison sage-grouse (GUSG) populations distributed across southwestern Colorado and southeastern Utah are described in the GUSG Rangewide Conservation Plan (see link to the Plan below). GUSG depend on sagebrush throughout much their life. The loss and fragmentation of sagebrush habitat may have important impacts on the long-term viability of GUSG populations, but the ecological mechanisms of these impacts are unknown. Our ability to conserve GUSG will depend on our ability to restore and protect a biologically relevant mosaic of habitats in a human-dominated landscape.
Three key assumptions made by biologists about the spatial ecology and population viability of a given species are: 1) demographic rates have significant influence on population persistence, 2) variation in demographic rates (due to environmental and demographic stochasticity) has a greater impact on small than large populations by significantly reducing persistence time, and 3) spatial variation in demographic rates and the ability to disperse can have a significant impact on species persistence time. The seven GUSG populations are likely to have different rates of demography and dispersal, as well as significant spatial and temporal variation (within and between populations). The effects of demographic stochasticity are likely to have a greater effect on persistence time in the smaller GUSG populations than in larger populations.
Population viability analysis (PVA) and spatially explicit population models (SEPM) are 2 analytical tools increasingly used by biologists to evaluate the relative effects of dispersal, demographic rates and changing landscape structure on the viability of small and declining species. PVA is a modeling approach to estimate the persistence time of a given species. SEP models evaluate the localized effects of landscape patterns on species distribution, abundance and population dynamics. SEP models are particularly useful for developing and evaluating alternative management strategies.
Information on the demographics and movement patterns of GUSG is necessary before constructing useful PVA and SEP models. The CPW has conducted research to evaluate seasonal use patterns of GUSG, but we still lack detailed information on demographics and dispersal patterns within and among populations - particularly, estimates of spatial and temporal variation.
Therefore, the objectives of this research projects are: 1) to acquire estimates of demographic rates with the appropriate estimates of temporal and spatial variation, 2) to record movement patterns, habitat use and dispersal capabilities of GUSG, 3) to continue the analysis of genetic diversity to improve the accuracy of estimates and to re-evaluate intra- and inter-population variability, 4) to use the above estimates to update and refine a PVA model and to develop a SEP model specific to GUSG and GUSG landscapes, 5) to contrast the demography, habitat use and dispersal patterns in a large population (the Gunnison Basin) with the smaller populations, and 6) to use estimates of demographic rates and model output to develop and evaluate the projected consequences of alternative management plans.
We will use radiotelemetry to track GUSG movements, and to estimate nest success and survival rates of juvenile and adult GUSG. Movement patterns, habitat use and dispersal capability will be analyzed using a GIS.
The 2005 field season was a pilot study to collect preliminary data and to evaluate alternative study protocols. I expect to collect an additional 3 years of data and to complete the SEP model and update the PVA model by 2010.