Laserfiche WebLink
<br />It is important to distinguish between a pattern of activities that is supportive of <br />populations and a single action which may actually kill, injure, or otherwise harm an <br />individual mouse. The former may provide long term support for a population and make <br />a net positive contribution to rangewide conservation. The latter may occur in the same <br />space and time or separately, but may kill or harm an individual mouse or preclude its <br />chances of successfully reproducing. <br /> <br />The recommendations herein are the consensus of the Science Team members which <br />were present at each of several meetings and conversations. The ranges of opinion <br />expressed on each question were wide. There. are few data to narrow the discussion, <br />making reasoning with the best available science as the prominent tool. For example, on <br />the issue of the distance separating an isolated patch of habitat from more suitable <br />reaches, some members of the team took the position that the distance of om: mile. <br />maximum observed movement by a pMJM in a single night was considerably too far. <br />Others believe it too small. In another case, when the team discussed the relative value of <br />upland foraging habitat to riparian shnlb vegetation, several team members expressed the <br />opinion that more foraging habitat could likely be altered than was determined through <br />consensus. They believed this to be the case especially when alterations were temporary. <br />However, data are not available to support larger areas or shorter distances. We noted <br />that the consensus opinions are in line with one of our Guiding Principles: conservative <br />conclusions are appropriate when the resolution from data is poor. <br /> <br />The team also discussed at length the i$sue of the very high standard of individual take <br />under the ESA compared to the relative insignificance of an individual mouse to large <br />populations. The former is more in line with the ESA's requirements, but the latter is <br />more aligned with the framework of ecosystem and population biology. Therefore, this <br />letter is intended to provide the best scientific information available to the USFWS and <br />other parties for use in the legal proces$. <br /> <br />Other issues pertinent to an appropriate interpretation of the recommendations are: <br />a.' We divided the PMlM habitat into shrubs and non-shrubs, but the forb <br />component, particularly the rank forbs (tall, non-grarninoid, herbaceous <br />plants), may be of disproportionate significance. However, forbsare not <br />distributed in a distinctive pattern or are not independent of shrubs. We <br />concluded that they are lIdequate1y incorporated in the recommendations. <br />b. Site-by-site evaluations must consider (in the calculations) non-habitat <br />(e.g., parking lots, roads, etc.). Site-specific evaluations will always <br />provide preferred information. <br />c. Several team members believe that larger areas than are indicated could be <br />impacted, but it was based on "gut-level" science. There were no data to <br />guide us in the creation of a recommendation or guideline more refined <br />than what is presented. <br />d. Principles of population ecology and conservation biology suggest that the <br />mortality of a single mouse is usually of small consequence. But this is <br />only true where the total population is large. The "conservation value" of <br />an individual mouse increases with decreasing population size. This is not <br /> <br />2 <br /> <br />. <br /> <br />.. <br /> <br />. <br />