Acknowledgments

1
Estimating Calf Elk Summer Survival Through
Aerial and Ground-Based
Classifications
Map of hunting district 292 study site outlined
in red and yellow
Ron Howell University of Montana, Project TRAIN
2004 Undergraduate Research Fellow
Abstract Calf elk recruitment, as indexed by
spring classification flights, has progressively
declined across western Montana, including upon
our study site in the Garnet Range, over the past
3 decades. We compare summer calf elk survival
estimates generated from regular ground-based and
aerial classifications to survival estimates
generated from a radio-marked calf elk sample.
Both aerial and ground techniques demonstrate
variability however, ground techniques were
highly variable. Both techniques tended to
underestimate survival compared to survival from
the radio-marked sample. We make several
recommendations to wildlife managers charged with
estimating summer elk calf survival.
Aerial photo of cow elk pushing calf elk

• Introduction
• Calf elk recruitment has progressively declined
  in west-central Montana over the past 3 decades,
  causing concern for wildlife managers.
• Calf 100 Cow ratios measured through spring
  green-up fixed-wing aircraft surveys show
  declines from 47 to 18 calves per 100 cows since
  1988 on our study site, Montana Department of
  Fish, Wildlife Parks (FWP) Hunting District
  292-00, in the Garnet Mountains (Fig 1).
• I participated in a study that is radio-marking
  newborn elk to determine if decreasing
  recruitment is primarily a function of inadequate
  nutrition, increased predation, or a low
  proportion of mature bulls.
• From summer 2002 to 2004, this study has
  systematically conducted regular calf cow
  classifications from fixed-wing aircraft to
  compare to calf survival estimates from
  radio-marked sample.
• I collected regular ground-based classifications
  in the summer of 2004 to compare to both aerial
  classifications and calf elk survival estimates.
• My primary objective is to provide information to
  wildlife managers about how summer ground-based
  classifications relate to aerial classifications
  and calf elk survival.

• Conclusions
• Ground-based classifications showed a high degree
  of variability throughout the summer while aerial
  classifications were moderately variable.
• In all but 3 instances, ground and aerial
  classifications underestimated calf elk survival
  relative to survival estimates generated from
  radio-marked sample.
• Ground-based classification survival estimates
  tended to be closer to survival estimates from
  radio-marked sample when a large total number of
  elk were observed.
• Management Recommendations
• Ground-based classifications may be used to
  estimate survival when habitat allows for regular
  observation of large numbers of elk.
• Wildlife managers should adjust for negative
  survival bias associated with ground-based
  classifications also, numerous observations are
  recommended due to high degree of variability.
• Wildlife managers should classify elk during the
  month of July as survival estimates generated
  from calf cow ratios are most representative
  then because calf cow pairs have joined massive,
  visible nursery groups.
• Aerial classifications may be used to estimate
  survival when ground-based techniques are not
  appropriate, but estimates must be adjusted.

• Results
• As of August 31, 2004 we have documented 7 elk
  calf mortalities from the 2004 radio-marked
  sample (14).
• Summer 2004 aerial calf 100 cow ratios have
  ranged from a high of 47100 (7/2) to a low of
  33100 (7/31) (Figure 2).
• Summer 2004 ground-based calf 100 cow ratios
  have ranged from a high of 100100 (7/14) to a
  low of 16100 (6/27) (Figure 2).
• Ground based classifications tended to show large
  variability relative to aerial classifications
  (Figure 2).
• Neither 2004 ground-based nor aerial calf
  survival estimates strongly correlated to calf
  survival estimates generated from the
  radio-marked sample however 2002 and 2003 aerial
  calf survival estimates did weakly correlate with
  survival estimates from calf sample (Figure 3).

• Materials and Methods
• From summer 2002 to 2004, we captured, processed,
  and radio-marked 121 newborn elk with
  mortality-sensing, radio ear tag transmitters and
  expandable, break-away radio collars.
• During each of the 3 field seasons, we conducted
  between 4 and 6 summer radio-telemetry flights
  from a Supercub aircraft counting and classifying
  elk as calves, cows, and spike, raghorn, and
  mature bulls. For each flight we generated a
  calf 100 cow ratio to estimate calf survival.
• In addition, during 2002 and 2003 we measured cow
  elk pregnancy rates, and age and sex structure of
  herds to determine how many calves are born
  annually on the study site. We estimate that
  roughly 67 calves are produced for every 100 cows
  in the elk herds on our study site.
• During the summer of 2004, I collected 10
  ground-based classifications on 2 herds
  (Kleinschmidt Murray) on our study site from
  6/22/04 to 8/31/04.
• I utilized radio-telemetry techniques in an
  attempt to locate elk herds at sunrise.
  Binoculars and a Bushnell 40X spotting scope were
  used to observe animals. I recorded date, time,
  weather, herd, UTMs from a Garmin GPS unit, and
  counted and classified total animals, including
  calves, cows, and bulls (spikes, raghorns, and
  matures). I then generated a calf 100 cow ratio
  for each classification.

Figure 2. Summer Radio-marked calf survival
overlaid with aerial and ground calf 100 cow
ratios. Every labeled apex represents a sample
point.
Photograph of July aerial classification
consisting of large calf cow nursery group

• Literature Cited
• Heisey, D.M., and T.K. Fuller. 1985. Evaluation
  of survival and cause-specific mortality rates
  using telemetry data. Journal of Wildlife
  Management 49(3)668-674.
• Pollock, K.H., S.R. Winterstein, C.M. Bunck, and
  P.D. Curtis. 1989. Survival analysis in
  telemetry studies the staggered entry design.
  Journal of Wildlife Management 53(1)7-15.
• Samuel, M.D., E.O. Garton, M.W. Schlegel, and
  R.G. Carson. 1987. Visibility bias during
  aerial surveys of elk in northcentral Idaho.
  Journal of Wildlife Management 51622-630.

Figure 3. Comparison of aerial and ground-based
calf survival estimates to calf survival
estimated from radio-marked sample throughout
summer 2004.
Figure 1. Spring elk counts and calf and bull
100 cow ratios on our study site from 1988 to
2004 (excluding 2002 because of inappropriate
aircraft).
Acknowledgments Research Mentors Jarod Raithel
Nyeema Harris Funding Project TRAIN
Undergraduate Research Fellowship, Salish
Kootenai College, University of Montana Special
Thanks Penny Kukuk, Pat Hurley, Samantha Grant,
Candace Tucker, Kqyn Kuka, Kari Signor, Jeremy
Longdon.