Arthur Neil Hitchcock, Jr.
DIETS OF SPRING − MIGRATING WATERFOWL IN THE UPPER MISSISSIPPI RIVER AND GREAT LAKES REGION
AN ABSTRACT OF THE THESIS OF
JAY HITCHCOCK, for the Master of Science degree in ZOOLOGY, presented on AUGUST 14, 2008, at Southern Illinois University Carbondale.
TITLE: DIETS OF SPRING − MIGRATING WATERFOWL IN THE UPPER MISSISSIPPI RIVER AND GREAT LAKES REGION
MAJOR PROFESSOR: Michael W. Eichholz
I evaluated diet and food selection of 5 species of spring-migrating female waterfowl including 3 dabbling ducks (Blue-winged teal, Anas discors, Mallard, Anas platyrhynchos, Gadwall, Anas strepera) and 2 diving ducks (Lesser Scaup, Aythya affinis, and Ring-necked duck, Aythya collaris). Diet was evaluated with regards to the proportion of invertebrates and seeds consumed, and compared to forage availability data collected in habitats available to them at 6 study locations throughout the Upper Mississippi River and Great Lakes Region. I found latitude (i.e., stage of migration), longitude, food availability, and date all influenced the diet of spring migrating waterfowl, with some factors having a stronger influence than others. I observed differing diet trends with regard to foraging guild (e.g., dabbling and diving ducks), as each foraging guild was represented by 1 species that was heavily dependant on invertebrates (dabbling duck – Blue-winged teal; diving duck – Lesser scaup) and 1 species that was heavily dependant on seeds (dabbling duck – Mallard; diving duck – Ring-necked duck). The proportion of invertebrate foods in the diet increased throughout spring for all species of waterfowl, suggesting the importance of invertebrate food sources during spring staging. Data from this study provides valuable information to habitat managers and conservationists wishing to improve spring habitat conditions for migrating waterfowl, which likely influences waterfowl productivity.
ACKNOWLEDGMENTS
Without the financial support of Ducks Unlimited, Inc. and several private donors, USFWS (Upper Mississippi River and Great Lakes Joint Venture), Ohio Division of Wildlife, Wisconsin DNR, Illinois DNR, Bruning Foundation, Christel DeHaan Family Foundation, Saginaw Bay Wetlands Initiative Network, Herbert H. and Grace Dow Foundation, Rollin M. Gerstacker Foundation, Waterfowl Research Foundation, Southern Illinois University Carbondale, and The Ohio State University this research would not have been possible.
Although he made it quite clear on several occasions that I was not the ‘sharpest tool in the shed’, I would like to thank my graduate advisor and friend, Dr. Michael Eichholz for allowing me to conduct this research and for his support, advise, and expertise throughout my years at SIU. I am greatly indebted to Dr. Joshua Stafford for his invaluable statistical expertise and for the hours he committed to editing and replying to thousands of questions and emails. I would also like to thank my other committee members, Dr. Tina Yerkes and Dr. Matt Whiles for taking interest in my research and providing editorial comments and professional advice.
My extensive data set would not have been possible without the countless hours in the field and laboratory of the many technicians that worked for us. Of those, I would like to personally thank Stephanie, Cassie, Zac, Kristopher, Tim, Nick, Brent, Bryan, Chris, Devan, John Fulcher, Big John, Sara, Adam, Melissa, and Rick for helping with duck collection and laboratory analyses of gut contents. Many thanks are due to collaboraters Rich Schultheis, Jake Straub, Kyle Loper, Dr. Robert Gates, and Dr. John Colucci for their dedication to the project and timely delivery of data. I have thoroughly enjoyed making new friends and colleagues at SIU, all of which have made my time here more enjoyable.
Thanks to several federal refuges, state wildlife areas, and private landowners for allowing this research to be conducted on their property. Specifically, Cypress Creek National Wildlife Refuge, Chautauqua National Wildlife Refuge, Horicon National Wildlife Refuge, Central Gun Club, Winous Point Hunt Club, and Bill and Vivian Young for providing us with housing during our field season. I am greatly appreciative of the logistical and fieldwork help by Aaron Yetter, Chris Hine, Dr. Joshua Stafford, and Randy Smith of the Illinois Natural History Survey Forbes Biological Station in Havana, IL.
I am especially indebted to my family for their love and support throughout my life and for supporting me as I follow my dream to be a wildlife/waterfowl biologist. To my wife, Randa, I would have to write another thesis to explain my gratitude and love for you. Your patience and love have upheld me throughout the writing process. No more graduate school – I promise! Just you, me, and Belle. And duck season!
TABLE OF CONTENTS
CHAPTER PAGE
ABSTRACT……………………………………………………………………………….i
ACKNOWLEDGMENTS………………………………………………………………...ii
LIST OF TABLES……………………………………………………………………......vi
LIST OF FIGURES…………………………………………………………………...…..x
GENERAL INTRODUCTION ………………………………………………………...…1
CHAPTER 1 – DIET OF MIGRATING WATERFOWL DURING SPRING
IN THE UPPER MISSISSIPPI RIVER AND GREAT LAKES REGION………….…....5
INTRODUCTION……………………………….………………………………………..5
Diet in Relation to Annual Life Cycle of Waterfowl ………...………………….5
STUDY OBJECTIVES …………………………………………………………………...7
METHODS ……………………………………………………………………………….8
Study Site Selection ……………………………………………………………...8
Study Species ………………………………………………………………...…15
Waterfowl Collection ……………………………………………………...……16
Laboratory Analysis …………………………………………………………....17
Statistical Analysis …………………………………………………………..…18
RESULTS ……………………………………………………………………………….20
Summary Statistics ……………………………………………………………..20
MANCOVA results ………………………………………………………….…31
Breeding vs. Non-breeding …………………………………………..…31
Diet ………………………….………………………………………….33
Blue-winged Teal Diets………..………………………………………..33
Mallard Diets …….......…………………………………………………43
Gadwall Diets ……………………….......……………………………....50
Lesser Scaup Diets …….......………………………………………...…55
Ring-necked Duck Diets ………......……………………………………61
DISCUSSION …………………………………………………………………………...65
Temporal and Latitudinal Variation in Spring Diet Within a Species …….....…74
Longitudinal Variation in Spring Diet Within a Species ……………………….76
CHAPTER 2 – FOOD SELECTION BY MIGRATING WATERFOWL
DURING SPRING IN THE UPPER MISSISSIPPI RIVER AND GREAT
LAKES REGION ………………………………………………………………………..80
INTRODUCTION ………………………………………………………………………80
Food Selection ……………………………………………………………….…80
STUDY OBJECTIVES ………………………………………………………………….83
METHODS …………………………………………………………………………..….85
Food Availability ………………………………………………………………85
Laboratory Analysis ……………………………………………………………87
Statistical Analysis ………………………………………………………….….88
RESULTS …………………………………………………………………………...…..89
Availability ……………………………………………….……………………..89
Blue-winged Teal Food Selection ……………………….……………...………89
Mallard Food Selection ………..........…………………………………………..91
Lesser Scaup Food Selection ……………………………………….………..…91
Ring-necked Duck Food Selection ………….....…………………………....….93
DISCUSSION …………………………………………………………………......……93
Food Selection ……………………………………………………………….....93
Blue-winged Teal …………………………………………….………......…94
Mallard ……………………………..………………………….………..…..95
Lesser Scaup ………………….........……………………..…………....…...97
Ring-necked Duck ……………………………………………….……....…99
CHAPTER 3 − IMPLICATIONS FOR WETLAND MANAGEMENT FOR
SPRING − MIGRATING WATERFOWL IN THE UMR/GLR…....……............……101
Management Implications ...............................................................................................101
Managing Wetlands for Invertebrates During Spring Migration ....................................102
Managing Wetlands for Seeds During Spring Migration ...............................................103
Challenges to Providing Habitat for Spring-Migrating Waterfowl ................................104
LITERATURE CITED …………..........……………………………………………….105
APPENDICES
Waterfowl Diets at Different Study Sites........…………...…………………………….114
VITA ……...……..……………………………………………………………………..162
LIST OF TABLES
TABLE PAGE
Table 1.1 Number of ducks collected in the Upper MS River and Great Lakes Region that contained food items during spring 2006 and 2007 (BWTE
= blue-winged teal, MALL = mallard, GADW = gadwall, RNDU =
ring-necked duck, LESC = lesser scaup, CA = Cache River, IR =
Illinois River, WI = Wisconsin, SR =Scioto River, LE = Lake Erie,
SB = Saginaw Bay) ...................................................................................21
Table 1.2 Aggregate percent (A) ± standard error and percent occurrence (O)
of food items in ducks (BWTE = blue-winged teal, MALL = mallard, GADW = gadwall, LESC = lesser scaup, RNDU = ring-necked duck) collected in the Upper MS River and Great Lakes Region during spring 2006 and 2007…….……….......................................................................21
Table 1.3 Aggregate percent biomass of animal
foods consumed by dabbling
ducks collected in the Upper MS River and Great Lakes Region during spring 2006 and 2007. If food items were < 1.0% aggregate mass,
they were listed as trace (tr.)......................................................................22
Table 1.4 Aggregate percent biomass of plant foods consumed by dabbling
ducks collected in the Upper MS River and Great Lakes Region during
spring 2006 and 2007. If food items were < 0.5% aggregate mass, they were listed as trace (tr.)..............................................................................24
Table 1.5 Aggregate percent biomass of vegetation consumed by dabbling
ducks collected in the Upper MS River and Great Lakes Region during
spring 2006 and 2007. If food items were < 0.1% aggregate mass, they were listed as trace (tr.) .............................................................................26
Table 1.6 Aggregate percent biomass of animal foods consumed by diving
ducks collected in the Upper MS River and Great Lakes Region during
spring 2006 and 2007. If food items were < 1.0% aggregate mass, they were listed as trace (tr.)..............................................................................27
Table 1.7 Aggregate percent biomass of plant foods consumed by diving
ducks collected in the Upper MS River and Great Lakes Region during
spring 2006 and 2007. If food items were < 0.5% aggregate mass, they were listed as trace (tr.)..............................................................................29
Table 1.8 Aggregate percent biomass of vegetation consumed by diving
ducks collected in the Upper MS River and Great Lakes Region during
spring 2006 and 2007.................................................................................32
Table 1.9 Results from the initial MANCOVA model evaluating the effects of
site, species (Sp), date (Jul), habitat (Hab), reproductive status (RS)
and year (Yr) on proportions of invertebrates and seeds consumed by
5 species of ducks collected in the Upper MS River and Great Lakes Region during spring 2006 and 2007.........................................................34
Table 1.10 Date of first and last dabbling duck collected at each study site in
2006 and 2007 ...........................................................................................37
Table 1.11 Results from a MANCOVA model evaluating the effects of site,
date (Jul), habitat (Hab), reproductive status (RS), and year (Yr)
on proportions of invertebrates and seeds consumed by blue-winged
teal in the Upper MS River and Great Lakes Region during spring
2006 and 2007............................................................................................38
Table 1.12 Results from a MANCOVA model evaluating the effects of transect
(Tran), date (Jul), habitat (Hab), reproductive status (RS), year (Yr) and
transect by year (Tran*Yr) on proportions of invertebrates and seeds consumed by blue-winged teal in the Upper MS River and Great Lakes
Region during spring 2006 and 2007………….........................................40
Table 1.13 Results from a MANCOVA model evaluating the effects of transect
(Tran), date (Jul), habitat (Hab), and reproductive status (RS)
on proportions of invertebrates and seeds consumed by blue-winged
teal in the Upper MS River and Great Lakes Region during spring
2006 ………...............................................................................................41
Table 1.14 Results from a MANCOVA model evaluating the effects of transect
(Tran), date (Jul), habitat (Hab), and reproductive status (RS)
on proportions of invertebrates and seeds consumed by blue-winged
teal in the Upper MS River and Great Lakes Region during spring
2007 …….....................................................................…..........................42
Table 1.15 Results from a MANCOVA model evaluating the effects of site,
date (Jul), habitat (Hab), reproductive status (RS), and year (Yr)
on proportions of invertebrates and seeds consumed by mallards
in the Upper MS River and Great Lakes Region during spring 2006
and 2007….................................................................................................46
Table 1.16 Results from a MANCOVA model evaluating the effects of transect
(Tran), date (Jul), habitat (Hab), reproductive status (RS), year (Yr) and
transect by year (Tran*Yr) on proportions of invertebrates and seeds consumed by mallards in the Upper MS River and Great Lakes Region during spring 2006 and 2007 ……................……………........................48
Table 1.17 Results from a MANCOVA model evaluating the effects of site,
date (Jul), habitat (Hab), and year (Yr) on proportions of invertebrates,
seeds, and vegetation consumed by gadwalls in the Upper MS River
and Great Lakes Region during spring 2006 and 2007………..................51
Table 1.18 Results from a MANCOVA model evaluating the effects of transect
(Tran), date (Jul), habitat (Hab), year (Yr) and transect by year
(Tran*Yr) on proportions of invertebrates, seeds, and vegetation consumed by gadwalls in the Upper MS River and Great Lakes Region during spring 2006 and 2007 ...……...........................………………......53
Table 1.19 Results from a MANCOVA model evaluating the effects of transect
(Tran), date (Jul), and habitat (Hab) on proportions of invertebrates,
seeds, and vegetation consumed by gadwalls in the Upper MS River
and Great Lakes Region during spring 2006 ………................................54
Table 1.20 Results from a MANCOVA model evaluating the effects of transect
(Tran), date (Jul), and habitat (Hab) on proportions of invertebrates,
seeds, and vegetation consumed by gadwalls in the Upper MS River
and Great Lakes Region during spring 2007 ………................................56
Table 1.21 Date of first and last diving duck collected at each study site in
2006 and 2007 ...........................................................................................59
Table 1.22 Results from a MANCOVA model evaluating the effects of site,
date (Jul), habitat (Hab), and year (Yr) on proportions of invertebrates
and seeds consumed by lesser scaup in the Upper MS River and Great
Lakes Region during spring 2006 and 2007…..........................................60
Table 1.23 Results from a MANCOVA model evaluating the effects of transect
(Tran), date (Jul), habitat (Hab), and year (Yr) on proportions of invertebrates and seeds consumed by lesser scaup in the Upper MS
River and Great Lakes Region during spring 2006 and 2007 ...................63
Table 1.24 Results from a MANCOVA model evaluating the effects of site,
date (Jul), habitat (Hab), and year (Yr) on proportions of invertebrates
and seeds consumed by ring-necked ducks in the Upper MS River
and Great Lakes Region during spring 2006 and 2007…..........................66
Table 1.25 Results from a MANCOVA model evaluating the effects of transect
(Tran), date (Jul), habitat (Hab), and year (Yr) on proportions of invertebrates and seeds consumed by ring-necked ducks in the
Upper MS River and Great Lakes Region during spring 2006
and 2007….……........................................................................................68
Table 2.1 Mean food availability (kg/ha) and standard error (SE) of seeds and
invertebrates found in shallow (for dabbling ducks) and deep (for
diving ducks) habitats during spring 2006………..…………………...…90
Table 2.2 Results of selection analyses for ducks collected at study sites in
the Upper MS River and Great Lakes Region (CA = Cache River, IR =
Illinois River, WI = Wisconsin, SR = Scioto River, LE = Lake Erie,
and SB = Saginaw Bay) during spring 2006. An “I” indicates selection
of invertebrates, “=” indicates consumption in proportion to
availability, and “S” indicates selection of seeds ….……………..…...…92
Table 2.3 Mean percentage of food items and standard error (SE) in diet of
dabbling ducks at study sites in the Upper MS River and Great Lakes Region during spring 2006 …….................………………………...……96
Table 2.4 Mean percentage of food items and standard error (SE)
in diet of
diving ducks at study sites in the Upper MS River and Great Lakes
Region during spring 2006 ……….......……………………..…………...98
LIST OF FIGURES
FIGURE PAGE
Figure 1.1 Location of the Upper MS River and Great Lakes Region with respect
to wintering and breeding grounds of ducks migrating through the
Upper MS River and Great Lakes Region (image taken from United
States Fish and Wildlife Service 2008) .... ..................................................9
Figure 1.2 Location of study sites in the Upper MS River and Great Lakes Region
(image provided by Jake Straub, The Ohio State University) ..................10
Figure 1.3 Percent of seeds and invertebrates in the diet of 6 species (BWTE
= blue-winged teal, MALL = mallard, GADW = gadwall, LESC =
lesser scaup, RNDU = ring-necked duck) collected in the Upper MS
River and Great Lakes Region during spring 2006 and 2007
(least-squares mean ± standard error). Different letters indicate significantly different means......................................................................35
Figure 1.4 Percent of seeds and invertebrates consumed by blue-winged teal at
6 locations (SR = Scioto River, LE = Lake Erie, SAG = Saginaw Bay,
CA = Cache River, IR = Illinois River, WI = Wisconsin) in the
Upper MS River and Great Lakes Region during spring 2006 and
2007 (least-squares mean ± standard error). Different letters indicate significantly different means ......................……………………..…….....39
Figure 1.5 Percent of seeds and invertebrates consumed by blue-winged teal at
western/eastern transect in the Upper MS River and Great Lakes
Region during spring 2006 (least-squares mean ± standard error). Different letters indicate significantly different means ................………44
Figure 1.6 Percent of seeds and invertebrates consumed by blue-winged teal at
western/eastern transect in the Upper MS River and Great Lakes
Region during spring 2007 (least-squares mean ± standard error). Different letters indicate significantly different means ....................……45
Figure 1.7 Percent of seeds and invertebrates consumed by mallards at 6
locations (SR = Scioto River, LE = Lake Erie, SAG = Saginaw Bay,
CA = Cache River, IR = Illinois River, WI = Wisconsin) in the
Upper MS River and Great Lakes Region during spring 2006 and 2007 (least-squares mean ± standard error). Different letters indicate significantly different means .............…………………………………....47
Figure 1.8 Percent of seeds and invertebrates consumed by mallards at
western/eastern transect in the Upper MS River and Great Lakes
Region during spring 2006 and 2007 (least-squares mean ± standard
error). Different letters indicate significantly different means ........……49
Figure 1.9 Percent of seeds, vegetation, and invertebrates consumed by
gadwalls at 6 locations (SR = Scioto River, LE = Lake Erie, SAG =
Saginaw Bay, CA = Cache River, IR = Illinois River, WI = Wisconsin)
in the Upper MS River and Great Lakes Region during spring 2006
and 2007 (least-squares mean ± standard error). Different letters
indicate significantly different means ...............………..……………......52
Figure 1.10 Percent of seeds, vegetation, and invertebrates consumed by gadwalls
at western/eastern transect in the Upper MS River and Great Lakes Region during spring 2006 (least-squares mean ± standard error). Different letters indicate significantly different means ................………57
Figure 1.11 Percent of seeds, vegetation, and invertebrates consumed by gadwalls
at western/eastern transect in the Upper MS River and Great Lakes
Region during spring 2007 (least-squares mean ± standard error). Different letters indicate significantly different means ................………58
Figure 1.12 Percent of seeds and invertebrates consumed by lesser scaup at 6
locations (SR = Scioto River, LE = Lake Erie, SAG = Saginaw Bay,
CA = Cache River, IR = Illinois River, WI = Wisconsin) in the
Upper MS River and Great Lakes Region during spring 2006 and
2007 (least-squares mean ± standard error). Different letters indicate significantly different means .........................………………………........62
Figure 1.13 Percent of seeds and invertebrates consumed by lesser scaup at
western/eastern transect in the Upper MS River and Great Lakes
Region during spring 2006 and 2007 (least-squares mean ± standard
error). Different letters indicate significantly different means …....……64
Figure 1.14 Percent of seeds and invertebrates consumed by ring-necked ducks
at 6 locations (SR = Scioto River, LE = Lake Erie, SAG = Saginaw
Bay, CA = Cache River, IR = Illinois River, WI = Wisconsin) in the
Upper MS River and Great Lakes Region during spring 2006 and
2007 (least-squares mean ± standard error). Different letters indicate significantly different means .........................………………………..…..67
Figure 1.15 Percent of seeds and invertebrates consumed by ring-necked ducks
at western/eastern transect in the Upper MS River and Great Lakes
Region during spring 2006 and 2007 (least-squares mean ± standard
error). Different letters indicate significantly different means ....………69