TO: David H. Riskind
FROM: Kelly B. Bryan and Linda K. Hedges
Regional 1 Resource Coordinator and Biology Field Worker
DATE: July 6, 1998
SUBJECT: Limpia Creek LIP effort adjacent to Davis Mountains State Park
RE: Reply to request for Resource Program imput
The following is a summary of our concerns and questions regarding the Limpia Creek LIP effort:
- Bulldozer work was conducted under an active Common Black-Hawk nest tree. During the actual work, Kelly Bryan observed the female parent off the nest, circling directly over the disturbed site and calling incessantly.
- On 6/23 Bonnie McKinney called Linda Hedges at our office and advised her that a survey conducted on 5/29 indicated that the project was authorized to proceed with respect to nesting songbirds (lack of) and the Common Black-Hawk nest and young. On 6/5 Linda Hedges showed birder from New Jersey the nest site (from the highway R.O.W.) and the female Common Black-Hawk appeared to be incubating. On 6/25 Linda Hedges received fax from Bonnie McKinney stating that the "Common Black-Hawks fledged young from the nest and the birds were visible" to her on 6/24. On 6/26, Kelly Bryan checked the hawk nest from the highway and observed a less than 10 day old downy white chick in the nest attended by the female adult hawk. On 6/29 and 7/1 a tour group from Missouri, led by Bill Roe, reported to Kelly Bryan that the first chick and the "runt" chick (half the size of the older chick) were observed under the female adult.
- The permanent stream was channelized, lowering the water table and separating the actual stream from the floodplain woodland. This is a known detriment to the floodplain ecosystem as a whole (Ohmart, 1996).
- The project was stated to be a "restoration" effort, yet bulldozing indiscriminately took out all undstory ground cover, shrubs and young trees, and some midstory trees. Included were sapling cottonwoods and willows that would have significantly contributed to the regeneration of the site.
- This project appears aimed at single species management and has failed to consider the overall biodiversity of the site, and in fact has drastically reduced such. Criteria that provide indices of reparian system health (Ohmart 1996) include 1) conditions of the banks and channel (in a natural state vegetated), 2) bank material not just stream bed rock conglomerate, but tied together with roots of trees, shrubs, grasses and sedges, 3) plant diversity in the stream and on the banks necessary for protecting the site from flood events, 4) maximum diversity in terms of species richness, vertical profile, and foliage density in both flora and fauna is a direct indicator of maximum ecosystem health, 5) stream banks containing a 5 cm root mix resist erosion 20,000 times better than non-rooted banks (Smith 1976), 6) presence of herbaceous coverage, and 7) an even distribution of age class vegetation in the floodplain woodland.
- Ohmart (1996) states that indicators of riparian system degradation include: 1) destruction of overhanging banks, 2) overburdened sediment loads, 3) stream channel changes, 4) virtual elimination of herbaceous ground cover and understory vegetation, 5) cessation of tree and shrub reproduction along floodplain. The work performed either contributed to or caused all of the above. Consequences include 1) severely impacted fish populations due to bank destruction channel widening, and high sediment loads, 2) higher water temperatures, lower oxygen levels, and reduced detrital due to elimination of understory trees and shrubs, further stressing fish and aquatic invertebrate populations, and 3) density declines in small mammals, birds, reptiles, and amphibians requiring dense herbaceous vegetation or dense understory vegetation.
- Was the status of this community type (the Cottonwood-Willow series) considered in the plan? TPWD documents classify this series as a G3 Global Rank and S3 State Rank which indicates that it is very rare, local and threatened throughout its range.
- The primary prey base for Common Black-Hawks is amphibians, Was this considered with respect to the impacts to the aquatic habitat?
- Were impacts to native fish fauna in the aquatic system of the site considered or even surveyed prior to the actual work?
- Although no livestock are present on the site currently, riparian habitats such as the project site are know to be one of the faster recovering habitat types in the southwestern desert region so long as all impacts are removed from the landscape. Simple fencing to exclude livestock from the immediate vicinity of the hawk nest would have allowed maximum and natural recovery of the site.
- The Common Black-Hawk nesting site is probably the best know site in the U.S. and is described in numerous publications. Its economic value to a private land owner via ecotourism is questioned due to its proximity to a public right-of-way, historic use and notoriety.
- The project area and Limpia Canyon ecosystem lie adjacent to and contiguous with that existing on Davis Mountain State Park, yet persons responsible for and familiar with the management of Limpia Creek within the park boundaries were not notified or consulted with regards to the biological context of the reparian system and its impending impacts.
- With the monsoon season here, woodland and reparian systems are poised for damaging impacts should heavy rains occur due to the fact that the entire floor of the woodland is denuded and exposed.
- Was an archeological review conducted under Section 106 of the National Historic Preservation Act (36 CFR 800)?
- What model was used in the formulation of plans for the work that was conducted? Are there references that support the project design as it was implemented?
Ohmart, R. D. 1996. Historical and present impacts of livestock grazing on fish and wildlife resources in western reparian habitats. ppg 245-279 in Rangeland Wildlife, Paul Krausman, ed.
Smith, DG. 1976. Affect of vegetation on laterial migration of anastomosed channels of glacier meltwater river. Bull. of Geological Socitey of American, 87: 857-860.