Ralph and others 



Chapter 1 



Overview of Ecology and Conservation 



used more than the lower volume productive stands in 

 southeast Alaska. The results of Kuletz and others (in press, 

 this volume) in Prince William Sound, Alaska, and Burger 

 (this volume) in British Columbia do, however, suggest that 

 stands with higher densities of old-growth trees have 

 characteristics associated with high murrelet use. We cannot 

 predict the trend of the remaining old-growth forests, as it 

 will depend on the final outcome of National Forest land 

 management plans. We expect further decline in area of 

 murrelet nesting habitat in regions where terrestrial habitat 

 loss continues, and we expect this decline to stabilize 

 eventually. But when, and at what level, this stabilization 

 will occur, is difficult to foresee. The apparent reduction of 

 the species' population by 50 percent in Alaska must be 

 viewed with concern. Similarly, in British Columbia, with 

 only about 30 percent of original coastal old-growth forest 

 remaining and a likelihood of further loss, we cannot predict 

 when the amount of suitable habitat will stabilize. 



On State lands, the status and trend of murrelet habitat 

 depends on state forest practice regulations and implementation 

 of take guidelines or Habitat Conservation Plans in 

 cooperation with the U.S. Fish and Wildlife Service under 

 the Endangered Species Act. In Washington, the State may 

 seek an incidental take permit in exchange for delineating 

 and protecting most currently occupied suitable habitat. 

 Future management is difficult to predict, as new information 

 may lead to revised definitions of suitable habitat and new 

 management strategies. On tribal lands, we do not have 

 information on likely management direction. On private 

 lands, reduction of habitat with apparent breeding behavior 

 is likely in the short term, but Habitat Conservation Plans 

 may be undertaken by larger land owners. These plans may 

 result in agreements to harvest some habitat in exchange for 

 deferral of harvest of other habitat. 



Population Trends 



As we have suggested, available evidence indicates that 

 the population of murrelets has declined over most of its 

 range. As more nesting habitat is lost, coupled with the adult 

 mortality in some areas from gill-net fisheries and occasional 

 oil spills, we expect continued decline in the population of 

 murrelets. The rate of future population decline may exceed 

 the rate of habitat loss because of cumulative effects on adult 

 survival. At-sea counts do not necessarily reflect breeding 

 density, as some lag is expected between reduction in the 

 nesting habitat and a decline in the at-sea population. Thus, 

 effects may not appear in the form of a declining population 

 for a decade or more. Murrelets are suspected to be long-lived, 

 and adults may survive at sea even if nesting habitat is 

 removed, perhaps leading to the low ratio of juveniles to 

 adults found in at-sea counts in recent years (Beissinger, this 

 volume). Reduction in prey, as might be occurring in recent 

 warm-water years (1992-93), may also lead to a lower 

 proportion of adults nesting and to lower reproductive success 

 among those birds that do nest. 



We do not have the necessary information to predict 

 what proportion of the current population can be lost without 

 irreversible consequences. The most prudent strategy for 

 now is to conserve those forest stands (where the species is 

 listed) that currently support murrelets within each 

 physiographic region; between these conserved areas, 

 additional areas should also be set aside to improve the 

 likelihood of recolonization of unoccupied areas. 



Some provision for catastrophic habitat loss and other 

 unpredictable events is a necessary component of a conser- 

 vation strategy. We cannot count on all areas of habitat to 

 persist indefinitely. The forests within the range of the Marbled 

 Murrelet are subject to periodic wildfire, to insect or disease 

 outbreaks, to large scale windthrow, and other catastrophic 

 losses. Managers will need to apply active management to 

 reduce risk of loss in some regions. We recognize, however, 

 that not all of these effects are bad, as some of these events 

 result in creation of nesting habitat by stimulating formation 

 of nesting platforms. 



The following key points are clear 



(1) Murrelet population trends will vary by region, in 

 relation to changes in the amount, distribution, protection, 

 and ownership of remaining forest habitat, catastrophic loss 

 of breeding habitat, prey abundance, and extent of mortality 

 factors, such as oil spills, gill netting, and predation on 

 adults and young. 



(2) A need exists to establish the relative importance of 

 nesting habitat versus other factors in causing population 

 trends. We assume that the trend in amount and distribution 

 of suitable nesting habitat is the most important determinant 

 of the long-term population trends. 



(3) Existing demographic methods do not permit analysis 

 of population trends in relation to variation in quality of 

 habitat (measured by amount and pattern of appropriate 

 forest structure), because of the cost of gathering such data. 



(4) Given current knowledge or demographic methods, 

 we are unable to know the likelihood that any population of 

 murrelets is approaching a demographic direshold from which 

 recovery may not be possible. 



(5) Net change in amount of habitat is a function of loss of 

 current habitat versus succession of potential habitat. If other 

 demographic characteristics prevent recovery as suitable habitat 

 stabilizes or increases (that is, if murrelet populations continue 

 to decline), then other factors are regulating the population. 



(6) Populations are relatively large in Alaska and British 

 Columbia, perhaps allowing more time to evaluate trends 

 than in other parts of the range. However, large population 

 declines in Alaska are, at least, cause for concern. Certainly, 

 throughout the range, immediate management efforts should 

 be directed towards maintenance of the North American 

 population at or near present levels. In Alaska and British 

 Columbia, we need an accelerated effort to better understand 

 murrelet ecology and habitat relationships through research 

 and surveys. These need to be initiated immediately, and a 

 conservative habitat management approach needs be adopted 

 in the interim. 



USDA Forest Sen-ice Gen. Tech. Rep. PSW-152. 1995. 



17 



