10 research outputs found
Surface Tension Chem Sci (2015) Paper
No full textExcel 2010 Spreadsheet containing data for seven figures appearing in: Chemical Science (2015) Precise, Contactless Measurements of the Surface Tension of Picolitre Aerosol Droplets Bryan R. Bzdek, Rory M. Power, Stephen H. Simpson, Jonathan P. Reid,* and C. Patrick Royall School of Chemistry, University of Bristol, Bristol, BS8 1TS UK Corresponding author: J. P. Reid ([email protected]
Manual of quantitative pathology in cancer diagnosis and prognosis. Author: J. P. A. Baak, Springer‐Verlag, New York, 1991
No full textLe verbe venir – esquisse typologique et essai de traduction en polonais de son emploi spatial français et espagnol
No full textThe main topic of this paper deals with a general typological survey of the spatial French and Spanish verb venir based on some linguistic studies chosen by the author (J.-P. Boons, 1987; A. Borillo, 1998; D. Bouchard, 1993; C. Vandeloise, 1986, 1987). This article analyses also the syntactic-semantic schemes of venir in the purpose of its translation into Polish. The author takes advantage in her analysis of the concept of the class of objects. The method of the study is based on object-oriented approach and the word sense disambiguation by W. Banyś.The main topic of this paper deals with a general typological survey of the spatial French and Spanish verb venir based on some linguistic studies chosen by the author (J.-P. Boons, 1987; A. Borillo, 1998; D. Bouchard, 1993; C. Vandeloise, 1986, 1987). This article analyses also the syntactic-semantic schemes of venir in the purpose of its translation into Polish. The author takes advantage in her analysis of the concept of the class of objects. The method of the study is based on object-oriented approach and the word sense disambiguation by W. Banyś
Le verbe "venir" - esquisse typologique et essai de traduction en polonais de son emploi spatial francais et espagnol
No full textSpanish verb venir based on some linguistic studies chosen by the author (J.-P. B o o n s, 1987 ;
A. B o r i l l o, 1998 ; D. B o u c h a r d, 1993 ; C. Va n d e l o i s e, 1986, 1987). This article analyses
also the syntactic-semantic schemes of venir in the purpose of its translation into Polish. The
author takes advantage in her analysis of the concept of the class of objects. The method of the
study is based on object-oriented approach and the word sense disambiguation by W. Banyś
Love Your God with All Your Mind: The Role of Reason in the Life of the Soul
No full textWe know that faith means “being sure of what we hope for and certain of what we do not see” (Hebrews 11:1, NIV). Love Your God with All Your Mind explains the importance of using your mind not only to win others to Christ but also to experience personal spiritual growth. Author J. P. Moreland challenges you to use logic and reason to further God’s kingdom through evangelism, apologetics, worship, and vocation. This revised edition includes expanded appendixes and three new chapters that outline how to reason for the reality of God and the historicity of Jesus’ life teachings, death, and resurrection.https://digitalcommons.biola.edu/faculty-books/1581/thumbnail.jp
LA PODEROSA THEMIS Y LA GALERÍA FÚNEBRE: UNA POLÉMICA EN PRENSA EN EL CONTEXTO DE LA TRADUCCIÓN DE COLECCIONES DE RELATOS EN ESPAÑA (1830-1831)
No full textBy means of a letter of protest sent by Julián Anento and Basilio S. Castilians to El Correo Literario y Mercantil in July, 1831, on the publication of Galería fúnebre by Agustín Pérez Zaragoza, and his reply in the same newspaper, one can appreciate the common identity of the original French author (J. - P. - R. - Cuisin) and different aspects of interest, in order to know the state of the art on translation in Spain in the final years of Fernando VII’s reign, particularly regarding the relationship between literature and journalism of that period.By means of a letter of protest sent by Julián Anento and Basilio S. Castilians to El Correo Literario y Mercantil in July, 1831, on the publication of Galería fúnebre by Agustín Pérez Zaragoza, and his reply in the same newspaper, one can appreciate the common identity of the original French author (J. - P. - R. - Cuisin) and different aspects of interest, in order to know the state of the art on translation in Spain in the final years of Fernando VII’s reign, particularly regarding the relationship between literature and journalism of that period.C’est à travers une lettre de protestation envoyée par Julián Anento et Basilio S. Castellanos au Correo Literario y Mercantil en juillet 1831 sur la publication de la Galería fúnebre, d’Agustín Pérez Zaragoza, et de sa réponse dans le même journal, que nous pouvons mettre en évidence l’identité commune de l’auteur original français (J.- P.- R.- Cuisin) et les différents aspects d’intérêt pour connaître la situation de la traduction en Espagne durant les dernières années du règne de Ferdinand VII, présentant ainsi un sujet concret des relations entre littérature et journalisme de l’époque
Accurate Measurements of Aerosol Hygroscopic Growth Over a Wide Range in Relative Humidity
No full textThe hygroscopic properties of aerosol govern the response of aerosol particle size and composition to the relative humidity of the gas phase. The data sets in this project are accumulated from single particle measurements of hygroscopic response made at the Bristol Aerosol Research Centre. Here, we include data for the publication: Journal of Physical Chemistry A (2016) Accurate Measurements of Aerosol Hygroscopic Growth Over a Wide Range in Relative Humidity Grazia Rovelli [1,2], Rachael E.H. Miles [1], Jonathan P. Reid [1],* and Simon L. Clegg [3] 1 School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK 2 Department of Earth and Environmental Sciences, University of Milano-Bicocca, 20124 Milan, Italy 3 School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, UK Corresponding author: J. P. Reid ([email protected]
Evaluation of rare earth elements (REEs) in selected Nigerian coal fly ash: a prelude to extraction and waste management
No full textAbstract
The rising need for rare earth elements (REEs) as critical materials for the development of clean energy technologies, as against the rapid depletion of virgin REE-bearing ores as well as their imbalance in geographical occurrence, calls for thorough search on secondary sources such as coal fly ash, given that the aluminosilicate mineral phase in the waste is enriched in REE particles. To support the geographical diversification of REE sources, there is a need for a comprehensive documentation of REE content and, by extension, the economic potential of fly ash derived from Nigeria's vast coal fields. Eight representative coal fly ash samples generated from coals from Nigeria's major coal belts were collected. Silica and alumina, with respective ranges of 38.1–44.5% and 14–15.98%, accounted for the bulk of the major elements in the samples. Total REE contents in the samples ranged from 874 ppm to 1127 ppm, while the cerium, yttrium, neodymium and lanthanum-dominated rare oxide totals were found to be in the range of 941–2145 ppm across the samples. The outlook coefficients (extractability indices) computed for the samples ranged between 0.8 and 1.3, with 0.7 as the benchmark. The range of percentage of critical REEs in the CFA samples was 28%–36%. This research has successfully explored the relative abundance and distribution of REEs in the studied fly ash samples, providing a theoretical lead for the basis of extraction and waste management.Abstract
The rising need for rare earth elements (REEs) as critical materials for the development of clean energy technologies, as against the rapid depletion of virgin REE-bearing ores as well as their imbalance in geographical occurrence, calls for thorough search on secondary sources such as coal fly ash, given that the aluminosilicate mineral phase in the waste is enriched in REE particles. To support the geographical diversification of REE sources, there is a need for a comprehensive documentation of REE content and, by extension, the economic potential of fly ash derived from Nigeria's vast coal fields. Eight representative coal fly ash samples generated from coals from Nigeria's major coal belts were collected. Silica and alumina, with respective ranges of 38.1–44.5% and 14–15.98%, accounted for the bulk of the major elements in the samples. Total REE contents in the samples ranged from 874 ppm to 1127 ppm, while the cerium, yttrium, neodymium and lanthanum-dominated rare oxide totals were found to be in the range of 941–2145 ppm across the samples. The outlook coefficients (extractability indices) computed for the samples ranged between 0.8 and 1.3, with 0.7 as the benchmark. The range of percentage of critical REEs in the CFA samples was 28%–36%. This research has successfully explored the relative abundance and distribution of REEs in the studied fly ash samples, providing a theoretical lead for the basis of extraction and waste management
Adaptive harvest management considerations for the 1998 duck hunting season
No full textadapt_harvest_ducks98.pdf1
Adaptive Harvest Management
Considerations for the
1998 Duck Hunting Season
PREFACE
The process of setting waterfowl hunting regulations is conducted annually in the United States. This process
involves a number of meetings where the status of waterfowl is reviewed by the agencies responsible for setting
hunting regulations. In addition, the U.S. Fish and Wildlife Service (USFWS) holds public hearings and
publishes proposed regulations in the Federal Register to allow public comment. This document is part of a
series of reports intended to support development of harvest regulations for the 1998 hunting season.
Specifically, this report is intended to provide waterfowl managers and the public with information about the
use of adaptive harvest management for setting duck-hunting regulations in the United States. This report
provides the most current data, analyses, and decision-making protocols. However, adaptive management is
a dynamic process, and information presented herein may differ from that published previously. Moreover,
the set of regulatory alternatives has not yet been finalized for the 1998 hunting season and, therefore, harvest
strategies presented in this report should be considered preliminary.
ACKNOWLEDGEMENTS
A working group comprised of technical representatives from the USFWS and the four Flyway Councils
(Appendix A) was established in 1992 to review the scientific basis for managing waterfowl harvests. The
working group subsequently proposed a framework of adaptive harvest management (AHM), which was first
implemented in 1995. The USFWS expresses its gratitude to the working group and other individuals,
organizations, and agencies that have contributed to the development and implementation of AHM. We
especially thank D. J. Case and Associates for help with information and education efforts.
This report was prepared by the USFWS Adaptive Management & Assessment Team, which is administered
by the Office of Migratory Bird Management and the North American Waterfowl and Wetlands Office. Fred
A. Johnson was the principal author. J. P. Bladen, R. J. Blohm, D. F. Caithamer, D. J. Case, J. A. Dubovsky,
K. Gamble, J. R. Kelley, W. L. Kendall, E. M. Martin, M. T. Moore, M. C. Otto, P. I. Padding, A. Romer,
S. E. Sheaffer, G. W. Smith, and K. A. Wilkins provided information or otherwise assisted with report
preparation. Comments regarding this document should be sent to Paul R. Schmidt, Chief, Office of Migratory
Bird Management - USFWS, Arlington Square, Room 634, 4401 North Fairfax Drive, Arlington, VA 22203.
Cover art: the 1935 duck stamp with a pen and ink drawing of canvasbacks
by Frank W. Benson, who has been called the dean of American duck etchers.
2
Annual reports on adaptive harvest management are available on the Internet at:
http://www.fws.gov/r9mbmo/reports/reports.html
TABLE OF CONTENTS
EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
BACKGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
MALLARD STOCKS AND FLYWAY MANAGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . 5
MALLARD POPULATION DYNAMICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
HARVEST MANAGEMENT OBJECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
REGULATORY ALTERNATIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
OPTIMAL HARVEST STRATEGIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
FUTURE CHALLENGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
APPENDIX A: AHM Working Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
APPENDIX B: Eastern Mallard Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
APPENDIX C: Past Regulations and Harvest Strategies . . . . . . . . . . . . . . . . . . . . . 26
3
EXECUTIVE SUMMARY
In 1995, the U.S. Fish and Wildlife Service (USFWS) embraced the concept of adaptive resource
management for regulating duck harvests in the United States. The adaptive approach explicitly
recognizes that the consequences of hunting regulations cannot be predicted with certainty, and
provides a framework for making objective decisions in the face of that uncertainty. Moreover,
adaptive harvest management (AHM) relies on the iterative cycle of monitoring, assessment, and
decision making to clarify relationships among hunting regulations, harvests, and waterfowl
abundance.
To date, AHM has focused primarily on midcontinent mallards, but progress is being made on
extending the process to account for mallards breeding eastward and westward of the midcontinent
region. The ultimate goal is to develop Flyway-specific harvest strategies, which represent an average
of optimal strategies for each mallard breeding population, weighted by the relative contribution of
each population to the respective Flyways. Geographic boundaries used to define midcontinent and
eastern mallards have been established, and mathematical models of population dynamics are available
for predicting regulatory impacts. Investigations regarding the geographic bounds and population
dynamics of western mallards are ongoing.
A critical need for successful implementation of AHM is a set of regulatory alternatives that remain
fixed for an extended period. When AHM was first implemented in 1995, three regulatory
alternatives characterized as liberal, moderate, and restrictive were defined based on recent regulatory
experience. The 1995 regulatory alternatives also were considered for the 1996 hunting season. In
1997, the regulatory alternatives were modified in response to requests from the Flyway Councils.
Changes included provisions for additional hunting opportunity under the moderate and liberal
alternatives, as well as the addition of a very restrictive alternative. For the 1998 season, the USFWS
wishes to maintain the same regulatory alternatives as those considered in 1997, although a final
decision is pending.
Preliminary harvest strategies were derived for midcontinent and eastern mallards, but they do not
yet allow for Flyway-specific regulatory choices. The strategy for midcontinent mallards was based
on: (1) an objective to maximize long-term harvest and achieve a population goal of 8.7 million; (2)
an assumption that regulatory alternatives will remain the same as in 1997; and (3) current
understanding of regulatory impacts. Based on a breeding population size of 10.6 million mallards
and 2.5 million ponds in Prairie Canada, the optimal regulatory choice for midcontinent mallards in
1998 is the liberal alternative. The strategy for eastern mallards was based on: (1) an objective to
maximize long-term harvest; (2) the regulatory alternatives for 1997; and (3) a “working model” of
population dynamics. Based on a breeding population size of 1.0 million mallards and spring
precipitation of 11.6 inches, the optimal regulatory choice for eastern mallards in 1998 also is the
liberal alternative.
Future challenges include: (1) stabilization of regulatory alternatives for an extended period; (2)
development of large-scale habitat monitoring programs; (3) further refinement of mallard population
models; and (4) agreement on the appropriate scales of adaptive harvest management.
4
BACKGROUND
The annual process of setting duck-hunting regulations in the United States is based on a system of
resource monitoring, data analyses, and rule making (Blohm 1989). Each year, monitoring activities
such as aerial surveys and hunter questionnaires provide information on harvest levels, population
size, and habitat conditions. This monitoring program represents the most comprehensive of its kind
for any widely distributed group of wildlife species. Data collected from this monitoring program are
analyzed each year, and proposals for duck-hunting regulations are developed by the Flyway
Councils, States, and U.S. Fish and Wildlife Service (USFWS). After extensive public review, the
USFWS announces a regulatory framework within which States can set their hunting seasons.
In 1995, the USFWS embraced the concept of adaptive resource management (Walters 1986) for
regulating duck harvests in the United States. The adaptive approach explicitly recognizes that the
consequences of hunting regulations cannot be predicted with certainty, and provides a framework
for making objective decisions in the face of that uncertainty (Williams and Johnson 1995). Inherent
in the adaptive approach is an awareness that management performance, in terms of sustainable
hunting opportunities, can be maximized only if regulatory effects can be predicted reliably. Thus,
adaptive management relies on the iterative cycle of monitoring, assessment, and decision making
described above to clarify the relationships among hunting regulations, harvests, and waterfowl
abundance.
In regulating waterfowl harvests, managers face four fundamental sources of uncertainty (Nichols et
al. 1995a, Johnson et al. 1996, Williams et al. 1996):
(1) environmental variation - temporal and spatial variation in weather conditions and other key
features of waterfowl habitat; an example is the annual change in the number of ponds in the Prairie
Pothole Region, where water conditions influence duck reproductive success;
(2) partial controllability - the ability of managers to control harvest only within limits; the harvest
resulting from a particular set of hunting regulations cannot be predicted with certainty because of
variation in weather conditions, timing of migration, hunter effort, and other factors;
(3) structural uncertainty - an incomplete understanding of biological processes; a familiar example
is the long-standing debate about whether harvest is additive to other sources of mortality or whether
populations compensate for hunting losses through reduced natural mortality; structural uncertainty
increases contentiousness in the decision-making process and decreases the extent to which managers
can meet long-term conservation goals;
(4) partial observability - the ability to estimate key population variables (e.g., population size,
reproductive rate, harvest) only within the precision afforded by existing monitoring programs.
Adaptive harvest management (AHM) was developed as a systematic process for dealing effectively
with these uncertainties. The key components of AHM (Johnson et al. 1993, Williams and Johnson
1995) include:
5
(1) a limited number of regulatory alternatives, which contain Flyway-specific season lengths, bag
limits, and framework dates;
(2) a set of population models describing various hypotheses about the effects of harvest and the
environment on waterfowl abundance;
(3) a measure of reliability (probability or "weight") for each population model; and
(4) a mathematical description of the objective(s) of harvest management (i.e., an "objective
function"), by which harvest strategies can be evaluated.
These components are used in an optimization procedure to derive a harvest strategy, which specifies
the appropriate regulatory choice for each possible combination of breeding population size,
environmental conditions, and model weights (Johnson et al. 1997). The setting of annual hunting
regulations then involves an iterative process:
(1) each year, an optimal regulatory alternative is identified based on resource and environmental
conditions, and on current model weights;
(2) after the regulatory decision is made, model-specific predictions for subsequent breeding
population size are determined;
(3) when monitoring data become available, model weights are increased to the extent that
observations of population size agree with predictions, and decreased to the extent that they
disagree; and
(4) the new model weights are used to start another iteration of the process.
By iteratively updating model weights and optimizing regulatory choices, the process should
eventually identify which model is most appropriate to describe the dynamics of the managed
population. The process is optimal in the sense that it provides the regulatory choice each year
necessary to maximize management performance. It is adaptive in the sense that the harvest strategy
“evolves” to account for new knowledge generated by a comparison of predicted and observed
population sizes.
MALLARD STOCKS AND FLYWAY MANAGEMENT
Since 1995, the AHM process has focused on midcontinent mallards, which are defined as those
breeding in federal survey strata 1-18, 20-50, and 75-77, and in Minnesota, Wisconsin, and Michigan
(Fig. 1). An optimal regulatory alternative for midcontinent mallards is based on breeding population
size and prairie water conditions, and on the weights assigned to the alternative models of population
dynamics. The same regulatory alternative is applied in all four Flyways, although season lengths and
bag limits are Flyway-specific.
Efforts are underway to extend the AHM process to account for mallards breeding westward and
eastward of the midcontinent survey area. These mallard stocks make significant contributions to the
total mallard harvest, particularly in the Atlantic and Pacific Flyways (Munro and Kimball 1982).
Extension of the current process to account for multiple mallard stocks and Flyway-specific
regulatory choices involves:
midcontinent
eastern
Mallard population:
6
(1) augmentation of the decision criteria to include population and environmental variables
relevant to eastern and western mallards;
(2) revision of the objective function to account for harvest management objectives for mallards
outside the midcontinent region; and
(3) modification of the decision rules to allow independent regulatory choices in the Flyways.
An optimal harvest strategy for each Flyway then can be derived, which in effect would represent an
average of the optimal strategies for each breeding stock, weighted by the relative contribution of
each stock to the respective Flyways.
For the purposes of this report, eastern mallards are defined as those breeding in survey strata 51-54
and 56, and in New Hampshire, Vermont, Massachusetts, Connecticut, Rhode Island, New York,
Pennsylvania, New Jersey, Delaware, Maryland, and Virginia (Fig. 1). Managers are in the process
of establishing the geographic bounds of western mallards (see page 10).
Fig. 1. Survey areas currently assigned to the midcontinent and eastern populations of mallards for purposes of harvest
management.
7
MALLARD POPULATION DYNAMICS
Midcontinent Mallards
Estimates of the entire midcontinent population (as defined above) are available only since 1992.
Since then, the number of midcontinent mallards has grown by an average of 8.9 percent (SE = 1.0)
per annum (Table 1).
Table 1. Estimatesa of midcontinent mallards breeding in the federal survey area (strata 1-18, 20-50, and 75-77) and
the states of Minnesota, Wisconsin, and Michigan.
Federal surveys State surveys Total
Year N SE N SE N SE
1992 5976.1 241.0 977.9 118.7 6954.0 268.6
1993 5708.3 208.9 863.5 100.5 6571.8 231.8
1994 6980.1 282.8 1103.0 138.8 8083.1 315.0
1995 8269.4 287.5 1052.2 130.6 9321.6 304.5
1996 7941.3 262.9 945.7 81.0 8887.0 275.1
1997 9939.7 308.5 1026.1 91.2 10965.8 321.7
1998 9640.4 301.6 979.6 88.4 10620.0 314.3
a In thousands.
ly, the dynamics of midcontinent mallards are described by four alternative models, whic
result fr s
e nt) about whether harvest is an additive or compensatory form of
m nd whether the reproductive process is weakly or strongly density
d lability limits reproductive success). The model with
ad hunting mortality and weakly density-dependent recruitment (S R t A W
conservative harvest strategy, whereas the model with compensatory hunting mortality and strongly
density-dependent recruitment leads to the most liberal strategy (S R ). The other two models (S R C S A S
and S R ) lead to strategies that are intermediate between these extremes. C W
Two other sources of uncertainty in mallard harvest management are acknowledged. Unpredictability
in environmental conditions is characterized by random variation in annual precipitation, which affects
the number of ponds available during May in Canada. There is also an accounting for partial
controllability, in which the link between regulations and harvest rates is imperfect due to
uncontrollable factors (e.g., weather, access to hunting areas) that affect mallard harvest. A detailed
description of the population dynamics of midcontinent mallards and associated sources of uncertainty
are provided by Johnson et al. (1997).
A key component of the AHM process for midcontinent mallards is the updating of model weights.
1996 1997 1998
Year
8
9
10
11
12
13
14
Population size (millions)
8
9
10
11
12
13
14
SaRs
SaRw
ScRs
ScRw
observed
8
These weights describe the relative ability of the alternative models to mimic changes in population
size, and they ultimately influence the nature of the optimal harvest strategy. Model weights are
based on a comparison of predicted and observed population sizes, with the updating leading to
higher weights for models that prove to be good predictors (i.e., models with relatively small
differences between predicted and observed population sizes) (Fig. 2). These comparisons must
account for sampling error (i.e., partial observability) in population size and pond counts, as well as
for partial controllability of harvest rates.
When the AHM process was initiated in 1995, the four alternative models of population dynamics
were considered equally likely, reflecting a high degree of uncertainty about harvest and
environmental impacts on mallard abundance. Model weights changed markedly in 1996, and have
remained relatively stable since (Table 2). On the whole, comparisons of observed and predicted
population sizes provide some evidence of strongly density-dependent reproduction, but little
indication of a compensatory response to hunting mortality.
Fig. 2. Estimates of observed mallard population size (solid bar) compared with predictions from four alternative models
of population dynamics (SaRs = additive mortality and strongly density-dependent reproduction; SaRw = additive
mortality and weakly density-dependent reproduction; ScRs = compensatory mortality and strongly density-dependent
reproduction; ScRw = compensatory mortality and weakly density-dependent reproduction).
Eastern Mallards
Midwinter counts and the Breeding Bird Survey provide evidence of exponential growth in the eastern
mallard population since the mid-1970s. This pattern of growth also is apparent in the more recent
fixed-wing (strata 51-54 and 56) and northeastern plot (New Hampshire south through Virginia)
surveys (Table 3), although population growth seems to have slowed in more recent years.
9
Table 2. Temporal changes in probabilities ("weights") for alternative hypotheses of midcontinent mallard population
dynamics.
Model weights
Mortality
hypothesis Reproductive hypothesis 1995 1996 1997 1998
Additive Strong density dependence 0.2500 0.6417 0.5668 0.6462
Additive Weak density dependence 0.2500 0.3576 0.4235 0.3537
Compensatory Strong density dependence 0.2500 0.0005 0.0082 0.0001
Compensatory Weak density dependence 0.2500 0.0002 0.0015 0.0000
Table 3. Estimatesa of mallards breeding in the northeastern U.S. (plot survey from New Hampshire to Virginia) and
eastern Canada (fixed-wing survey strata 51-54 and 56).
Plot survey Fixed-wing survey Total
Year N SE N SE N SE
1990 665.1 78.3 190.7 47.2 855.8 91.4
1991 779.2 88.3 152.8 33.7 932.0 94.5
1992 562.2 47.9 320.3 53.0 882.5 71.5
1993 683.1 49.7 292.1 48.2 975.2 69.3
1994 853.1 62.7 219.5 28.2 1072.5 68.7
1995 862.8 70.2 184.4 40.0 1047.2 80.9
1996 848.4 61.1 283.1 55.7 1131.5 82.6
1997 795.1 49.6 212.1 39.6 1007.2 63.4
1998 775.1 49.7 263.8 67.2 1038.9 83.6
a In thousands.
The population dynamics of eastern mallards were studied extensively by Sheaffer and Malecki
(1996), but managers have not yet established a set of alternative models that characterize key
uncertainties about the mortality and reproductive processes. In the interim, a “working model” has
been developed to help managers understand the potential biological impacts of the current AHM
process on eastern mallards.
The working model of eastern mallards incorporates natural mortality rates that are similar to those
of midcontinent mallards and an assumption of completely additive hunting mortality. Reproductive
rates are predicted based on the size of the population and regional precipitation during March-May
of the current year. The reproductive process is characterized as strongly density dependent,
predicting the highest reproductive rates during years in which population size is relatively low and
spring precipitation is high. Mathematical details of the working model for eastern mallards are
provided in Appendix B.
0 1 2 3 4 5 6 7 8 9 10
Harvest value (%)
100
80
60
40
20
0
Expected population size next year (in millions)
population
goal = 8.7
10
Western Mallards
The analyses necessary to incorporate western mallards into the AHM process are ongoing. Initial
work has focused on delineating population boundaries by examining the geographic distribution of
recoveries from birds banded in various breeding areas. Mallards banded in the Pacific Flyway states,
British Columbia, the Yukon Territories, and southern Alberta have similar band-recovery
distributions, suggesting they share breeding, migration, and wintering areas. This analysis has
prompted concern over whether mallards in southern Alberta should be reassigned from the
midcon
