Field Notes: A Lynx or Not?
Last summer federal researchers confirmed that five wildcats found in northeastern Minnesota and Maine were hybrids between bobcat and Canada lynx-the first ever reported outside of captivity.
According to Len Ruggiero, project leader of the forestry sciences lab at the U.S. Forest Service's Rocky Mountain Research Station in Missoula, Mont., researchers hope to obtain funding to investigate why hybridization occurs and what the long-term impact might be on lynx populations. Interest is keen because, under the Endangered Species Act, the Canada lynx is listed as threatened in its entire U.S. range.
Wildlife biologists confirmed three hybrids after analyzing DNA from hair and tissue samples from 19 cats in Superior National Forest in northeastern Minnesota. Examining samples collected in Maine later in the summer, researchers confirmed two more hybrids.
Ruggiero and Michael Schwartz, leader of the Missoula station's genetics laboratory, said the follow-up study would require collection of hair and tissue samples from sites where lynx and bobcat populations overlap. Besides northern Minnesota, such sites are found in Washington, Montana, Wyoming, Idaho, and Colorado.
Researchers will also examine hair and tissue samples from lynx and bobcat specimens preserved 10 to 150 years ago. According to Schwartz, preserved tissue might indicate if the species hybridized in the past.
But even if evidence proves lynx and bobcats produced hybrid offspring in the past, Ruggiero said future lynx management depends on learning how hybridization occurs in the wild and how often it occurs today. "People tend to jump to the conclusion that if historical hybridization occurred, then what we're finding today is no big deal," Ruggiero said. "The real issue is what's going on today-we need to understand the nature and extent of hybridization now."
The Canada lynx is about the same size as the more common bobcat (20 to 44 pounds). Bobcats look similar to lynx, but their feet and ear tufts are noticeably smaller, and their tail is whitish on the underside and at the tip. Lynx have no white on the tail tip. Bobcats are generally redder than lynx, and may have more distinctive dark spotting on their fur. Unlike bobcats, lynx are highly adapted to live where there is deep snow; thus the two species are isolated from each other in winter. The discovery of lynx-bobcat hybrids in the wild could mean contact between the two species is more common than once thought.
Researchers want to learn how Canada lynx and bobcats interbreed and whether the hybrids can reproduce. If hybrids can reproduce, they would dilute the genetic purity of Canada lynx populations. Management of this rare species would then become more complex.
"It would make it difficult to know from a management standpoint what we are trying to protect if we have animals with genes from both Canada lynx and bobcat," Ruggiero said. Even if hybrids cannot reproduce, he said, the female lynx's ability to produce more Canada lynx is reduced by giving birth to hybrids.
DNA analysis has shown that all five hybrids resulted from male bobcats breeding with female lynx. More samples will help determine if male lynx and female bobcats breed. "The discovery can be seen as a negative whether the hybrid offspring can reproduce or not," Ruggiero said. "It's probably more negative if the offspring are fertile because of the genetic dilution."