This study aimed to 1) create a stable isotope reference for common Arctic berries, 2) determine if coastal and interior berries have detectable isotope differences, and 3) assess the role of interior spring staging areas in pre-nesting nutrient acquisition by Cackling Geese. Stable isotope analysis was performed on berries and goose tissues. Results showed large variations between berry isotope values, making it impossible to distinguish coastal from interior berries. Goose samples also exhibited variations, though some females showed extensive follicle growth indicating pre-nesting nutrient acquisition. Future studies should involve larger berry samples and integrate egg isotope data to better understand goose nutrition before breeding.

1. Figure 1: Pictures of the four berry species sampled in this study. Lowbush blueberry,
crowberry, lowbush cranberry and alpine bearberry.
OBJECTIVES
 Create a stable isotope reference for common arctic
berries for future diet studies.
 Determine if a detectable difference in isotope signature
exists in coastal versus interior acquired berries.
 Assess the role and importance of interior staging
areas of the Y-K Delta in pre-nesting nutrient acquisition.
A Preliminary Assessment of the Role of Interior Spring Staging Areas and Acquisition of Berries in
Influencing Pre-Breeding Condition of Cackling Geese on the Yukon Delta NWR
Callie B. Moore1 , Kyle A. Spragens1,2
1 U.S. Fish & Wildlife Service, Yukon Delta National Wildlife Refuge, P.O. Box 346, Bethel, AK 99559
2 U.S. Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field Station, 505 Azuar Dr., Vallejo, CA 94592
METHODS
 Stable Isotope analysis was performed on
samples of four berry species; crowberry
(Empetrum nigrum), alpine bearberry
(Arctostaphylos rubra), lowbush cranberry
(Vaccinium vitis-idaea) and lowbush
blueberry (Vaccinium uliginosum). They
were collected from interior, mid-interior and
coastal locations when available.
 To compare isotopic information in two
different elemental turnover tissues,
abdominal (ab.) fat and liver samples were
collected from adult geese harvested during
the spring migration by subsistence hunters.
 Stable Isotope analysis for nitrogen and
carbon were run on all samples.
INTRODUCTION
It is well documented in literature that some arctic nesting
geese forage on berries in tundra habitats during late summer
and fall. However, there is a lack of sufficient data on the use of
berries from interior regions of the Yukon-Kuskokwim Delta
NWR prior to nest initiation. The presence of vent staining on
harvested Cackling Geese (Branta hutchinsii minima) led us to
hypothesize that interior overwintering berries may play a
more significant role in reproduction than originally
believed and we sought to find out which berries they utilize.
DISCUSSION
• Geese sampled did not exhibited any evidence of vent
staining. We speculate that timing of harvest may have
influenced this. We believe that geese collected later in
the season would be more likely to show evidence of
vent staining (as has been suggested by local hunters).
 Lack of snow cover throughout the Y-K Delta resulted
in a limited number of over wintering berry crops (2013
berries) which only permitted the use of some over
wintered berries in our study. Coastal and mid-interior
samples were supplemented with fresh (2014) berries.
 Peak goose migration through Bethel was atypical in
spring 2014, unseasonably warm temperatures reduced
snow cover required for subsistence hunter travel,
resulting in a limited number of cacklers available for
sampling.
RESULTS
 13 tissue samples (7 liver and 6 ab. fat) were collected from seven different
cackling geese during early spring migration – one goose did not exhibit enough
fat to collect the corresponding ab. fat sample.
 5 of 6 ab. fat samples resulted in δ15N values < the limit of quantification
(LOQ).
 Large variations in berry sample measurements yield results that are not
mutually exclusive.
 In 4 of 5 females sampled extensive follicle growth was noted and one female
who displayed no signs of follicle growth had no ab. fat sample taken.
 Large variation in N isotope values for all berry samples make it impossible to
detect a difference in signatures for coastal versus interior regions.
-34.00
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-8.00 -6.00 -4.00 -2.00 0.00 2.00 4.00 6.00 8.00 10.00
δ13CvsVPDB
δ15N vs air
Interior Crowberry
Interior Bearberry
Interior Cranberry
Mid Crowberry
Mid Bearberry
Mid Blueberry
Costal Crowberry
LIVER
ABDOMINAL FAT
Figure 3: Raw data values comparing δ13C & δ15N measurements. Circles depict the large overlap between all four berry species
STUDY SITE
Four locations on the Y-K Delta were chosen due to
accessibility of field camps. Kigigak Island and
Manokinak River locations (coastal), Kgun Lake
(intermediate) and Bethel (interior).
FUTURE STEPS
 Perform larger scale berry sampling to ensure
sufficient sample size and attempt to collect berry
samples all in the same time period (overwinter).
 Integrate egg isotope analysis and cackler tissue
sampling from coastal regions to reflect breeding.
 Standardize preparation techniques to prevent
contribution to variability in sample measurements.
 Consult literature and align sample preparation
techniques to those used in the most recent
studies (e.g. for berries should the flesh, seed or
both be used in analysis?)
Figure 2: Study sites used on the Y-K Delta in relation to other landmarks
Figure 4: Follicle development in migrating females harvested on May 1, 2014
ACKNOWLEDGEMENTS
Dedicated to Dennis G. Raveling who left us the cackling goose riddle yet to be solved
that inspired this project. Brian McCaffery and the Yukon Delta NWR staff and pilots for
exceptional logistic support, Professor Mark Dzurko from Fleming College for guidance
on data analysis, Matthew Rogers from the UAA ENRI Stable Isotope Laboratory for
running our samples and Lizzi Bonczek for assisting with berry collection.
 Sulphur isotope analysis was not completed in
time to be included in results, but may provide
further insight to berry differentiation.