Between 2007 and 2008, devastating heat and tick infestations cause Isle Royale moose population to only increase by 68%

Wolf, Moose, Tree - Part 1 of 2 - Climate Change (apparently posted in Nov. 2008)

"Maybe the most intriguing single finding is that the trees on Isle Royale fluctuate in their own growth patterns depending on how many wolves there are. So, the wolves are indirectly affecting tree growth because wolves affect the number of moose, and the moose eat trees. And so, you can actually see the ebb and flow of the wolf population by counting tree rings and measuring the ring width...

...wolf and moose populations are shrinking there. According to Science News, "Five of the last six summers have been the hottest in half a century."

"Hot summers are hard on moose," said (John) Vucetich.* "Hot weather causes moose to rest more and forage less," he explained, "and summer foraging is how moose prepare to survive the long, bitter winters."

"Warm springs and falls may also promote breeding of winter ticks, a species of tick that feeds on moose. The past five warm years have brought devastating tick infestations to Isle Royale. "The ticks weaken the moose and make them vulnerable to wolves," Vucetich explained. "The loss of blood caused by the ticks can even kill the moose outright."3

Here are the numbers: 2000 = 1,100 moose on the 210 square mile island. 2007 = Fewer than 400.

Encouraging Results from the Annual Study of Moose and Wolves

April 6, 2008. (AP) A 50-year-old research project on predator/prey relationships has found gains in the moose and wolf populations on Lake Superior's Isle Royale in the past year.

The study, which is considered the longest-running study of its kind in the world, found that the number of wolves on the lake's biggest island have increased from 21 in 2007 to 23 in 2008 and grew from three to four packs.

An estimated 385 moose were found on the island last year. This year's count was estimated at 650, according to the study.
...
Vucetich said researchers were also surprised that the moose population perhaps increased this year. Seven of the past 10 summers have been among the warmest in 50 years. When temperatures are above 55 degrees, moose begin to feel heat stress, Vucetich said.