'Unknown' wolf visitors, rebuffed incest, hungry moose highlight new Isle Royale report
May 03, 2019 02:12PM
● By Editor
By Tanda Gmiter of Mlive.com - May 3, 2019
ISLE ROYALE, MI - The annual report on Michigan's Isle Royale wolf and moose populations has been released. And unlike recent years where island-watchers were just waiting to see if the remote island's last two wolves had survived another year while the number of moose steadily ticked upward, this year's report has a little drama tucked inside its pages.
There are new wolves to track, intense territorial patrolling by the two old island-born wolves, some bared-teeth rebuffing of incestuous courtship, and even some "unknown" wolf tracks that likely show a group of mainland wolves visited the island for a few days this winter and sampled some moose kill leftovers.
So grab your popcorn and we'll take you through some of the report's best highlights.
It's compiled each year by researchers at Michigan Technological University. This winter, they spent four weeks tracking moose and wolves using planes and skis. Now in its 61st year, it is the world's longest-running study of a predator-prey relationship.
Yes, there's the expected rise in moose, this year topping 2,000. Their numbers have been allowed to grow nearly predator-free for years in the face of the island's dwindling wolf pack. Their population is at near record-high levels, and their browsing diet is putting a big dent in the wilderness island's vegetation, researchers found.
But the report also highlights some big moments among the wildlife on this Michigan island archipelago, which sits in Lake Superior about 15 miles from the Canadian mainland, and 60 miles from Michigan's Upper Peninsula.
The National Park Service kicked off a multi-year wolf relocation project last fall in hopes more predators would keep the booming moose numbers in check. The two island-born wolves - an older, related pair that can't have viable offspring - have been joined so far by 13 new wolves from Minnesota and Canada.
The Michigan Tech team was on the island during a window this winter when the island-born wolves and two new female wolves from Minnesota were there. The new wolves from Canada had not yet arrived, though recent GPS data from their tracking collarsshows how they are all fitting in.
Here are the highlights, new photos, and tracking maps, courtesy of the MTU study:
Island-Born Wolf Pair
The only two island-born wolves left from Isle Royale's old Chippewa Harbor Pack, this father-daughter pair had been the only wolves left on the island for several years.
Their family tree's DNA is too twisted to result in viable pups. They share the same mother, too, so they are also half-siblings. A pup they had in 2014 was visibly deformed and died at about 9 months old, researchers estimate.
Still, the male, age 10, and the female, 8, remain "tightly bonded and highly territorial," say researchers, who had good opportunity to study their movements in February and early March.
They were seen spending a lot of time patrolling the east end of Isle Royale, which is considered their home territory.
And as researchers have seen before with these two, the female wolf "soundly rejected the courtship advances of her father during the 2019 mating season," even showing off her bared teeth, just to make sure she got her point across.
During their winter study, researchers estimated 10 moose kills by wolves, and another 2 moose that died likely due to an accident or possibly malnutrition, between Jan. 21 and March 2.
This means the island's four resident wolves at that point were likely very well-fed.
A map included in the report shows the moose-kill spots.
During the bulk of the winter, just the two female Minnesota wolves and the island-born wolf pair were roaming the island. GPS trackers and overhead surveys showed the new arrivals were mostly keeping to themselves - and even traveled together at times - but their tracks crossed at enough points where the older wolves were surely aware of the Minnesota wolves' presence, researchers said:
"The island-born pair remained together at the east end of the island. The two Minnesota-born females remained alone, at the far west end of the island through February. These two females, new to the island, killed moose calves on their own. They were unusually sedentary throughout February when mating usually occurs. They may have been positioning themselves for maximum exposure to any males that might travel the shorelines at the west end ... However, the male Ontario-born wolves did not start arriving on the island until the very end of the breeding season and shortly thereafter. The movements and activity of all Minnesota-born and Ontario-born wolves will be closely monitored over the upcoming months via their GPS-collars by the NPS."
While observing wolf movements on the island, researchers came across some unfamiliar tracks that didn't originate from the two island-born wolves, or match up to the GPS-tracked movements of the new wolves.
Those tracks also generated some intense interest from the island-born wolf pair, who examined them at length.
Researchers believe these were wolves visiting from the mainland who crossed an ice bridge created by this year's very cold winter winter weather. They shared a lot of fascinating details about this incident:
"On February 13, tracks of an unknown wolf were observed near Daisy Farm, the day after the island-born pair had been observed scent-marking the same area. On February 19, the island-born pair was observed in Lane Cove inspecting tracks that appeared to have been left by an unknown wolf, possibly different from the first unknown wolf as its tracks were very large. (We investigated both sets of tracks from the ground—giving us reason to think they were left by different-sized wolves.)
"On the same day, 10 miles to the southwest of Lane Cove, we followed tracks of three wolves off and on for 50 miles, beginning along the north shore of Isle Royale, then continuing all the way to the southwest end, on and over a couple offshore islands, around to the south shore of the island where the wolves fed on a moose carcass (which probably died from malnutrition). The tracks then continued along the shore to Houghton Point, at which point the tracks were lost as they crossed the vast expanse of ice covering Siskiwit Bay. The island-born pair spent much of February 19-25 patrolling their territory, following the unknown-wolf tracks and leaving prominent double scent-marks along the way.
"During the week that remained of the winter study, we flew the shorelines and much of the eastern interior, but found no more tracks that appeared to be from unknown wolves. It can be difficult to draw inferences from observing tracks when those tracks do not lead to directly observing the wolves that made them. However, it’s highly unlikely that these unknown wolf tracks could have been left by either of the two Minnesota-born female wolves because GPS data from these collared wolves places them at the other end of the island during this period.
"Our best (though fallible) inference is that several wolves arrived to Isle Royale by crossing the ice bridge and then returned to the mainland after spending approximately a week on Isle Royale in February. If that inference is incorrect and one or more of these putative wolves remained on Isle Royale, then there is a good chance of detecting their presence within the next 12 months through fecal DNA. Alternatively, if one or more of these putative wolves contributes reproductively to the island, then that contribution will eventually be detected through the fecal DNA of their offspring."
To read more of this original article and read related reporting, follow this link to the mlive.com website. https://expo.mlive.com/news/g66l-2019/05/07b41c79418851/unknown-wolf-visitors-rebuffed-incest-hungry...