A. Status of the Spectacled Eider - U.S. Fish and Wildlife Service

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concordance in their descriptions of the eiders’ decline. Neither of the two most precise surveys (one aerial, one ground-based), however, were designed specifically to monitor numbers ofSpectacled Eiders. Manipulation of these databases to include inter-survey comparisons and restratification may lead to survey modifications that will yield a more precise estimate of the breeding population and its trend. With the exception ofa small data set from the Prudhoe Bay oil fields and traditional ecological knowledge from Wainwrigbt, no trend data exist for Spectacled Eider populations on the NS or in AR. Further, with the exception of a crude estimate from the Indigirka Delta, there are no estimates of historical population sizes in either of these two regions. Accurate and precise estimates of sizes and trends of populations will be needed for evaluating whether or not these populations meet the criteria for reclassification. Therefore, it is important that recently-initiated survey efforts on the NS and in AR be continued and enhanced with consideration of the effort needed to obtain the precision achieved on the YKD. For all surveys, a power analysis should be conducted. In other words, the probability of detecting a true change in population size must be determined, and surveys should be refined accordingly to improve preclslon. c. Population Dynamics--Although trend data can indicate the overall response of a population to its environment, such data alone can neither illuminate the causes for such responses nor predict the probabilities of specific responses in the future. Questions concerning population dynamics fall within the scope ofpopulation modeling and demographics. Among various types of population models, population viability analysis (PVA) has become almost d~ rigour in recovery planning for endangered species. PVA can generate estimates for minimum viable population sizes at varying levels of risk (i.e., probabilities oflong-term persistence). PVA has limitations, however, and such an approach is not necessarily appropriate in all circumstances. Specifically, it is inappropriate to use demographic data from a declining population (such as the Spectacled Eider population on the YKD) to conduct a PVA. As an exercise, however, PVA can help to guide decisions about research priorities and recovery criteria. Population modeling, including PVA, will be a central aspect of Spectacled Eider recovery planning, both during and beyond the exploratory phase of data collection. Initially, this modeling will highlight critical data gaps. Then, as life history data accumulate, the models should become increasingly robust and predictive and, thus, should allow evaluation of hypotheses addressing the cause(s) of the eiders’ decline and assessing obstacles to recovery. In addition, some models may help us assess the urgency of required actions if populations slip toward extinction. For stable or growing populations, minimum viable population models should allow us to estimate the time needed for recovery, and, for planning purposes, the cost of that recovery. 42
Quantitative criteria for reclassifying and deisting Spectacled Eiders are proposed in this document. These criteria, however, were developed in the general absence ofbasic demographic data for this species. Similarly, the population model presented in Appendix Ill represents, at best, a crude estimate, since many of the data used in generating this model were derived from similar species for which data are available. To be able to develop models with greater predictive power and delisting criteria with stronger foundations, we must obtain accurate and precise estimates for critical demographic variables, such as adult survival, juvenile survival, fecundity, and age at first breeding. Data-rich population models also will be important for evaluating hypotheses used in - - addressing the cause(s) of the Spectacled Eider’s decline. For example, estimates ofadult female survivorship can be used to test the null hypothesis that the decline was caused by excessive adult female mortality. Strong evidence refuting this hypothesis would allow investigators to move on to a consideration of other hypotheses. If, however, the survivorship data indicate that a certain age or sex class is exhibiting a disproportionately high mortality rate, research efforts can be reoriented to target that portion of the population. Such focused research increases the likelihood of both discovering the primary causes of decline and identifying current obstacles to recovery. A final benefit of robust demographic data pertains to population monitoring. Two methods are available for monitoring populations of free-ranging vertebrates: field surveys and demographic analyses. As population size and density increase, field surveys are more powerful than demographic analyses. At very low population sizes and densities, however, a demographic analysis of population trends becomes increasingly powerful (Taylor and Gerrodette 1993). If Spectacled Eider populations continue to decline, this alternative method for evaluating population trends may become necessary. d. CQnlaniin~nls--In recent years, several species of marine vertebrates have exhibited population declines or reproductive failures in the Bering Sea and North Pacific. One hypothesis to account for these declines and failures suggests that animals high in the food chain are accumulating dangerous levels ofenvironmental contaminants. Although the links between specific contaminant levels and reductions in survival and reproduction remain to be demonstrated in many cases, apparently high concentrations of certain contaminants have been discovered in several species of northern marine birds and mammals. Preliminary assessments of contaminants in Spectacled Eiders have not been encouraging: at several sites on the YKD, some nesting eiders are accumulating lead on the breeding grounds, and subsequent death by lead poisoning has been confirmed (Franson et al., 1995). Analyses of a limited sample of Spectacled Eider carcasses and feathers suggest that cadmium, selenium, and strontium occur at levels considered elevated in other species. Because of the insidious nature of environmental contamination and the current paucity of 43
Page 2 and 3: SPECTACLED EIDER RECOVERY PLAN Team
Page 4 and 5: LITERATURE CITATION U.S. Fish and W
Page 6 and 7: EXECUTIVE SUMMARY OF THE RECOVERY P
Page 8 and 9: TABLE OF CONTENTS DISCLAIMER PAGE 1
Page 10 and 11: LIST OF FIGURES Figure 1. Breeding
Page 12 and 13: A. Status of the Spectacled Eider R
Page 14 and 15: ) a) j~ 25000 0 2 220000 C ~15000 ~
Page 16 and 17: B. Causes for Decline and Obstacles
Page 18 and 19: Increasing interest in avicultural
Page 20 and 21: Other conservation measures include
Page 22 and 23: D. Natural History of the Spectacle
Page 24 and 25: Figure 4. Yukon-Kuskokwim Delta loc
Page 26 and 27: DEL?A RUSSIA SPECTACLED EIDER RANGE
Page 28 and 29: helicopter surveys in the Prudhoe B
Page 30 and 31: geographic populations, because imm
Page 32 and 33: Figure 8. Study sites and land stat
Page 34 and 35: their diseases (e.g., Schiller 1954
Page 36 and 37: E. Distinct Population Segments The
Page 38 and 39: A final consideration involves info
Page 40 and 41: Trend data are analyzed to inform w
Page 42 and 43: Figure 10. A hypothetical posterior
Page 44 and 45: thresholds are not “magic numbers
Page 46 and 47: Criteria for Reclassifying from Thr
Page 48 and 49: Criteria for Delisting from Threate
Page 50 and 51: The final aspect ofSpectacled Eider
Page 54 and 55: data on both levels and effects oft
Page 56 and 57: implicated. In the absence of histo
Page 58 and 59: . - currently small size of the YKD
Page 60 and 61: implementation of the Memoranda ofA
Page 62 and 63: . take of Spectacled Eiders. In add
Page 64 and 65: . AlS. Produce a handbook summarizi
Page 66 and 67: . Bl.4. 1.3. Develop visibility cor
Page 68 and 69: B2. 1.1. Implement YKD satellite tr
Page 70 and 71: . Appendix Ill). Since epidermal ag
Page 72 and 73: . feasible if post-fledging staging
Page 74 and 75: presumed that their activities have
Page 76 and 77: contaminants within Spectacled Eide
Page 78 and 79: limited ability to withstand additi
Page 80 and 81: surface after a year and is no long
Page 82 and 83: . The reproductive stages (eggs, yo
Page 84 and 85: is inadequate to sustain “normal
Page 86 and 87: ___________ 1967. The geese of the
Page 88 and 89: Dementev, G.P., and N.A. Gladkov (e
Page 90 and 91: ___________ 1 964a. Observations on
Page 92 and 93: Nelson, E.W: 1887. Report upon natu
Page 94 and 95: ________ P.R. Wade, R.A. Stehn, and
Page 96 and 97: Robert M. Platte, Migratory Bird Ma
Page 98 and 99: KEY Task Duration and Costs TBD - T
Page 100 and 101: TASK 324.2 I 12.4.1 .2 PRIOR- — 2
Page 102 and 103:
TASK I — [37 E12 EI.3 fTYU —PRI
Page 104 and 105:
TASK PRIOR- Dj ITYU — — A12.3 2
Page 106 and 107:
— TASK U — 135.2 PRIOR- TASK DE
Page 108 and 109:
TASK U PRIOR- ITY U TASK DESCRIPTIO
Page 110 and 111:
TASK PRIOR. U — DS.3 3 TASK DESCR
Page 112 and 113:
The final risk factor is the effect
Page 114 and 115:
This PVA will treat two population
Page 116 and 117:
Both aerial surveys are conducted a
Page 118 and 119:
0.2 0.15 -j i 4 0.1 0 -I 0.05 0.08
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emaining before the population reac
Page 122 and 123:
) critical population size; and (2)
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40%. The population growth rate cri
Page 126 and 127:
Table 1-2. Results of simulation wh
Page 128 and 129:
Hilborn, R. and C.J. Walters. 1992.
Page 130 and 131:
APPENDIX II TECHNICAL DETAILS OF TH
Page 132 and 133:
The likelihood function for the par
Page 134 and 135:
initial sample. Then the O~ were re
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LU ~0.8 z -J ~0.6 I-ET1 w107 480 m1
Page 138 and 139:
LITERATURE CITED APPENDIX LI De la
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where x = age. The fertility rate i
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of older females: (1) older females
Page 144 and 145:
RESULTS Solutions for single cause
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0.1 0.08 ~0.06 4 0 0.04 0. 0.02 0 0
Page 148 and 149:
growth rate. Perhaps this can be mo
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decline, by far the fastest way to
Page 152 and 153:
LITERATURE CITED APPENDIX In Bailli
Page 154 and 155:
APPENDIX IV SPECTACLED EIDER RECOVE
Page 156 and 157:
APPENDIX V COMMENTS RECEIVED ON DRA
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A. Status of the Spectacled Eider - U.S. Fish and Wildlife Service

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