Although everyone would prefer to see moose in their natural habitat, these moose calves appear to be thriving at the Minnesota Zoo. Six calves that were abandoned by their mothers were transported there by the Minnesota Department of Natural Resources (DNR) this summer.
Minnesota Department of Natural Resource (DNR) moose project leader Glenn DelGiudice said he is happy with the way that the second-year moose calf mortality study has gone so far. Abandonment rates of calves by mothers are way down from last year, and much of that is because of new techniques used to capture and collar the calves, typically at 48 hours old. “We feel very good about the capture techniques we are using right now,” DelGiudice said.
There are still some mysteries surrounding abandonment, said DelGiudice.
“We had a mother leave her calf for an hour after capture, then come back. Then leave again after several hours and come back to her calf again, only to leave and abandon the calf. We don’t know why,” he said.
In late spring DelGiudice and his crew captured and collared 25 calves. DelGiudice has a small crew to help him, which includes PhD graduate student Bill Severud and field biology tech, Tyler Obermoller. He also has three to six people—temporary field biology techs and volunteer graduate students—to assist him depending upon the time of year and the fieldwork that needs to be accomplished.
Each moose calf collar the team fits on a moose calf is fitted with a global positioning system (GPS). The mothers, called dams, have previously been fitted with GPS collars and are part of a larger mortality study of adult moose.
The 25 calves (11 females, 14 males) were captured and collared between May 8 to June 19 from 19 dams.
Unlike last year, no helicopters were used. It was thought that the noise and collaring had something to do with 11 calves being abandoned and then dying within the first couple of days of the study last year.
But that doesn’t seem to be the case.
Of the first week, May 8-15, DelGiudice said, “Our phase 1 capture approach was with three to four people per team with a handling time of approximately five minutes per calf (including weighing, measuring hind leg length and taking rectal temperature, sex determination, ear-tagging, and fitting of global positioning system collar). We captured 12 calves. This included some pauses for early minor adjustments to the approach.
“Seven of these 12 were abandoned, but following our Abandonment Contingency Plan, developed with a consulting veterinarian and the Minnesota Zoo, six of the seven were recovered in good condition and brought to the Minnesota Zoo. Five of them are being kept by the Minnesota Zoo and are on exhibit; the sixth one was or is being shipped to a zoo in Ohio.”
DelGiudice said the team held off recovering the seventh calf because they thought it was having contact with its dam. “The calf had been with its mother for a number of hours immediately after capture, so we delayed attempting a recovery so as not to interfere. That one calf died just before we decided to proceed with a recovery,” said DelGiudice.
On May 21 after a week of evaluating the capture technique, DelGiudice said, “We began our Phase 2 capture approach, two person per team, sex determination and GPS collaring only—handling time of one minute or less per calf (or for twins) with a strategy to be as “small and quick as possible.”
According to DelGiudice, “This capture approach was very successful. At the very end [June 19] only one dam abandoned late-born twins. We recovered these when it was clear the dam was not coming back…when the team arrived, one calf had already died, but the other was quite viable and running around. The calf was brought back to another facility with captive moose.”
Still, DelGiudice admitted that a late season capture from a dam calving so late in the season was risky. “Although it is important from a research perspective to distribute captures throughout most of the calving season… next year we will not likely capture that late in the season,” he said.
Researchers monitor the moose via computer. When a GPS shows that a moose hasn’t moved for more than 8 hours, researchers presume the moose has died and they try to retrieve the carcass within 24 hours. That allows them to more easily determine what has killed the adult or calf before smaller predators or bugs get to it and hamper their research.
Because of the new technology, DelGiudice said, “We can practically follow them in real time.”
The study of moose calf mortality using GPS collars is the first of its kind. “This should be of benefit to other wildlife researchers who may undertake similar studies,” he said.
The information may help scientists figure out what has caused the moose herd in Minnesota to drop 50 percent (8,867 to 4,300) in the last four years.
“Our sample size for studying natural mortality is markedly smaller this year due to the time and effort required to identify the best capture approach, so the results must be interpreted cautiously. However, wolf predation and bear predation were the most common causes of mortality in 2013 and 2014.”
This year four calves were killed by wolves and one by a bear. One other calf was abandoned due to an umbilical infection, which went systemic, said DelGiudice.
Last year 11 of 49 calves fitted with GPS collars died of complications immediately following capture, mostly because their mothers abandoned them. That led to the new capture approaches used this year.
As the 2013 study went on it was learned that wolves killed 16 calves, two were abandoned, one drowned, bears killed four and one died of unknown causes.
“Between the 2013 and 2014 field seasons, we have 40-50 collared calves from which to study natural survival rates and specific causes of natural mortality.
“The reason it ranges from 40-50, is because some of these new collars slipped off the calves prematurely after varying periods of time post-capture (up to 91 days). Some collar slipping is expected due to the thick brush, etc., that the moose move through, but the goal is to keep it to a minimum. The data collected up to the point of slipping are valid; however, we will be requesting the GPS collar manufacturer in Berlin, Germany to make modifications to the design for next year.
“With our new capture approach, we hope to be able to capture 50-60 calves next season to bring the total biologically useful sample size up to about 100 calves.”
Until then DelGiudice and Severud and the rest of his team, “will be doing two-three weeks of intense fieldwork conducting habitat assessments of pre-calving, calving, and mortality sites right after the leaf-off sometime in October, attempting to determine components or characteristics of sites that moose dams may select for and to identify deficiencies that may contribute to the vulnerability of calves to various causes of mortality,” DelGiudice said.
Asked if his department will receive any of the money generated from the sale of the recently issued moose license plates, DelGiudice said no. The Reinvest in Minnesota (RIM) money from license plate sales can be used for moose habitat work, but not moose population studies. He said the most recent funding cycle of the Legislative- Citizen Commission on Minnesota Resources granted funds for adult and calf moose studies totaling $600,000 for 2015-2017.
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