Ralph and others 



Chapter 1 



Overview of Ecology and Conservation 



varying types and degrees of fragmentation will provide the 

 information on the direct effects of forest management on 

 this source of mortality. Predation rates can be altered by 

 forest types also, as the exposure of nests becomes greater 

 with a more open forest. These data can be taken at the same 

 sites as the surveys for murrelets described below. 



Population Size and Trends 



The sizes of populations in most of the range have only 

 been approximated. Intensive surveys by air or sea can 

 provide at a minimal cost a reliable index of population 

 size. This is especially critical in Washington and Oregon, 

 but is needed in most other areas of the range as well. Since 

 definitive long-term trend data are lacking in virtually all 

 populations, and are absolutely necessary for comparing the 

 effects of management, succession, stochastic events, or the 

 aging of the murrelet population, immediate efforts should 

 be initiated to establish long-term studies. Calibration of 

 at-sea survey techniques, including determination of the 

 time of year when surveys are best done to determine 

 population size, are needed. As part of this study, the 

 hypothesized relationships between numbers of murrelets 

 seen offshore, the number of detections during dawn watches, 

 and the number of murrelets nesting in a stand should be 

 tested. We recommend convening a workshop to evaluate 

 at-sea sampling and data analysis methods. 



Demographic Information 



The methods of determining the demographic parameters 

 of murrelets need to be expanded and refined. At present, 

 observations of nests and the finding of young at sea provide 

 the only clues about the demography of the species. These 

 methods need to be continued and expanded, and new 

 methods devised. 



Limitations of Fish Stocks 



We do not know if the availability offish species important 

 to murrelets has declined, because the relationship of the 

 abundance and distribution of the several species taken by 

 the bird and the interplay of the behavior and distribution of 

 foraging birds is unknown. Use of bioacoustics could provide 

 the data on fish abundance and distribution simultaneous 

 with information on the birds' distribution, abundance, and 

 foraging. We urge that these methods be implemented in at 

 least two or three regions immediately. These methods would 

 provide a basis for establishment of marine reserves to provide 

 a source of abundant food fish for critical key areas of 

 murrelet feeding, as well as providing a source of fish stocks 

 for surrounding areas. Part of this research would include 

 studies on the food habits of the murrelet. 



Genetic Structure of Populations 



Determinations should be made about the size of the 

 various gene pools, the relative divergence of the populations, 

 and the importance of gaps in distribution. We need genetic 

 samples taken from throughout the range of the species. 



Colonial! ty and the Saturation of Nesting Sites 



The degree of clumping of murrelet nests should be 

 determined on a stand, forest, and landscape basis, once 

 sufficient data on nest locations are available. A determination 

 should be made about the extent to which behavioral spacing 

 mechanisms used by muirelets affect the density of birds in 

 a stand and the potential for selective harvest of trees. 



Effects of Human Disturbance 



Both in forests and at sea, the effects of various types of 

 human disturbance should be evaluated in controlled 

 experiments. It is not necessary to conduct these experiments 

 in areas where timber harvesting is being carried out, as the 

 noise and traffic of such activities are easily simulated. 



Conclusions 



We conclude that the stabilization and recovery of 

 murrelet populations will be aided by (1) provision of adequate 

 nesting opportunities, (2) elimination of sources of adult 

 mortality by human impact and development, and (3) 

 management to minimize loss of nest contents to predators. 



Specifically, we suggest the following steps be taken: 



1. Maintain a well-dispersed Marbled Murrelet popu- 

 lation, with each segment of the species' range managed to 

 maintain a viable population. Nesting habitat appears to be a 

 primary limiting factor in maintaining murrelet populations. 

 We feel any futher reduction in nesting habitat or areas for 

 the murrelet in Washington, Oregon, or California would 

 severely hamper stabilization and recovery of those populations 

 to viable levels. Occupied habitat should be maintained as 

 reserves in large contiguous blocks and buffer habitat sur- 

 rounding these sites should be enhanced. 



Progress in attaining population stablization or enhance- 

 ment can be measured by an increase in the productivity of 

 the population, by increases in the total breeding population, 

 an increase in the ratio of juveniles to adults in offshore 

 population, and an increase in nesting success. It is critical 

 that relevant agencies move quickly to put in place monitoring 

 programs suggested above which can provide at least some 

 of these data. 



2. We suggest management for the murrelet on a regional 

 basis, such as the Conservation Zones recommended by the 

 U.S. Marbled Murrelet Recovery Team (U.S. Fish and Wildlife 

 Service, in press). We strongly urge that objectives by 

 management agencies be based on biological processes, not 

 on political or administrative boundaries, as much as possible. 

 The overall goal should be to maintain a well-dispersed Marbled 

 Murrelet population, with each segment of the species' range 

 managed to maintain a viable population. 



3. Draft a landscape-based habitat conservation plan 

 within each of the nine zones described above to ensure the 

 maintenance of a viable population. As a result of this step, 

 the suggested reserves would likely need to be augmented to 



USDA Forest Service Gen. Tech. Rep. PSW-152. 1995. 



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