In 1973, the US Fish and Wildlife Service listed the northern Rocky Mountain wolf (Canis lupus) as an endangered species and designated Greater Yellowstone as one of three recovery areas. From 1995 to 1997, 41 wild wolves from Canada and northwest Montana were released in Yellowstone National Park.
Most chemical tests for pregnancy look for the presence of the beta subunit of hCG, or human chorionic gonadotropin, in the blood or urine. hCG can be detected in urine or blood after implantation, which occurs six to twelve days after fertilization.
Qualitative hCG testing detects the presence of hCG and is routinely used to screen for a pregnancy. This test may be performed by a laboratory, at a doctor's office, or at home using a home pregnancy test kit.