It could be the rustling sound of leaves or a sudden movement in a nearby bush.
Whatever the cause, many University students have experienced some uneasiness when walking around campus. Some may dismiss the feelings as part of an overactive imagination, but for others the reality of the sounds may be more frightening.
After four recent sexual attacks on women, including two female University students, the atmosphere on campus has become more guarded. Police have not determined a pattern in the latest assaults.
Some women have heeded warnings from authorities to be more careful, but others are not changing their habits. Whatever they decide, Ann Arbor's history of sexual attacks - including a serial rapist case two years ago - and today's concerns about campus safety cannot be ignored.
Residence halls work closely with the Sexual Assault and Prevention Awareness Center to educate students on campus safety and provide any necessary counseling.
Alan Levy, director of public affairs for University Housing, said the residence halls offer self-defense workshops periodically and hold discussions about sexual assault at floor meetings. Housing security officers can also talk to residents about crime prevention, Levy said.
"There is no acceptable boundary of sexual assault, and we don't have any tolerance of violations in this area," Levy said.
Safety tips have to be repeated often, so people do not relax their guard, Levy said.
"Some research indicates safety precautions not practiced will go by the wayside," Levy said. "If you go through a time when there's no bad incidents, people think it's OK to take shortcuts on public safety.
"Unfortunately we don't live in a world like that," he said.
Living in University residence halls is a common experience shared by new students, but some female students said they find coed halls more unsettling than all-female halls.
"I feel like everything over in Stockwell is so much more calmer," said LSA sophomore Shalonda Hunter, who lives in the single-sex Stockwell residence hall. "It's just not a lot of things moving.
"If you go over to the (coed) quads, people are always coming in and out," Hunter said.
LSA sophomore Cynthia Chin, who lives in Helen Newberry residence hall, agrees the all-female halls are safer because there is less traffic, but she said she worries about unfamiliar people who come in behind other residents.
"In a way, I do feel safer because it is a smaller dorm," Chin said. "You can recognize people and their friends. There are people hanging outside the door. They're waiting to get in. They haven't called anyone to come get them."
All entrances to Newberry and neighboring Betsey Barbour are locked. Only residents can gain access to the dorms by using ID scanners.
Nursing first-year student Jessica Inwood said students constantly let other people into the Mary Markley residence hall, where she lives, and they never get checked.
"I don't really feel that it's that safe because anyone can get in," Inwood said. "They lock the doors at 10 (p.m.), but if you're standing outside with your card, you open the door for someone who's waiting outside.
"It happens a lot," she said. "I do it."
Inwood suggested the University implement a system similar to Michigan State University's security plan, where guards stationed at residence hall entrances check student identification cards.
"There needs to be some kind of way you can tell who comes in and out of dorms," Hunter said. "It's 30 minutes away from a major city. Some random man or woman can come up to a dorm and do God knows what.
"They need some way to monitor, but some cases you can't stop it," Hunter said.
Several female students said they feel unsafe when it gets dark on campus.
"If I'm walking someplace, it's not one type of person you get that weird feeling (from)," Chin said. "You can feel someone's eyes on you."
Women just have to stay alert about a potential assault to protect themselves, LSA first-year student Kirsten Meister said.
"I think the people that don't think about it are naive and who it happens to," Meister said. "A lot of females think it's not going to happen to them. They're invincible.
"It's going to be a rude awakening when it does," Meister said.
Last Thursday, the Residence Halls Association met to address the latest rash of sexual assaults. RHA voted unanimously to accept the Residential Security Act, which creates a new security task force.
The task force plans to address several issues, including guest check-ins, 24-hour lock-down policies, the efficiency of security and emergency phones, and the installation of ID scanners at all residence halls.
The Greek system does not differ significantly from the residence halls on policies about sexual assault.
Since chapter members are governed foremost by the Code of Student Conduct, the Greek system has no specific sexual assault policy, said Becca Coggins, president of the Panhellenic Association.
"Individual chapters do have policies, and they all differ," Coggins said. "Chances are, national organizations will revoke membership if a member is convicted of a criminal sexual conduct."
Coggins said all Greek members are scheduled to participate in new programs on assault prevention this year. Officers from each Greek house undergo training about the realities of sexual assault, statistics and prevention techniques.
Several sorority members said they enjoy more security living in a sorority house than a residence hall.
"Living here is a lot safer because there's always someone to walk with," said LSA sophomore Ann Freeman, a member of Pi Beta Phi. "People don't slip through the cracks as easily. We always have people to watch out for each other."
Security alarms, locked doors and no male residents also make sorority houses a safer place to live, several women said.
"At the dorms they do have security guards," said LSA junior Kristin Barczuk. "Some guy tagging along would be more obvious in a sorority house than in a dorm."
LSA junior Anne Bratzel said her Alpha Chi Omega house is safe because doors are locked and equipped with an alarm system.
"We do have a policy on male visitation, so there can't be a random guy wandering around without people noticing," Bratzel said. "It's probably safer."
Students do not have to make the trek home alone when it is late at night. The University's Department of Public Safety and SAPAC co-sponsor two walking programs that are now in their 10th year.
Safewalk serves students on Central Campus from its office in the Shapiro Undergraduate Library lobby, seven days a week. Northwalk provides the same assistance for people on North Campus.
Since the recent increase in sexual assaults, Safewalk co-coordinator Andrea Lee said there has been a corresponding increase in the number of walks.
Lee said Safewalk is considering opening at 6 p.m. when it gets darker. Currently, both programs are open from 8 p.m. to 2:30 a.m. Sunday to Thursday and from 8 to 11:30 p.m. on Fridays and Saturdays.
"In response to a series of assaults on and around campus in 1986, (Safewalk) started as a cooperative between West Quad and Betsey Barbour/Helen Newberry (residence halls)," said Lee, an LSA senior. "It's definitely a comfort service."
Safewalk co-coordinator Nichole Argyres said the service does not discriminate against men or women, groups or individuals.
"For the people who get walked, they get to go wherever they need to go," Argyres said. "They're not restricted. It's a good way to meet people."
The number of walks requested fluctuates, Argyres said.
"We usually have fewer walks per night in the beginning of fall because it doesn't get dark as soon," Argyres said. "We'll have fewer walks when it's really cold outside, but when the serial rapist was around (in 1994) our walks doubled."
Students are walked from anywhere on campus to a desired location, which is usually 20 minutes away from the Undergraduate Library. Interested persons can obtain "a walk" by calling Safewalk at 936-1000 or Northwalk at 763-WALK.
"People who don't feel comfortable walking alone at night have the option to use us as well as other available options," Lee said.
The University also provides several late-night ride options, including the Nite Owl, Nite Ride and Ride Home. The Nite Owl is a free shuttle bus service running seven days a week and ending at 2 a.m. Nite Owl has specific stops around campus.
Nite Ride and Ride Home are taxi services. Nite Ride charges $2 and takes a person anywhere in the city. Ride Home requests, which do not cost anything, have to be made at the Undergraduate Library or the North Campus Commons between 2-7 a.m.
Two years ago the city of Ann Arbor was visited by something more menacing than the winter season.
Theories of a serial rapist that were splashed across local headlines in May 1994 became more justified when Ann Arbor police named the man accused in previous assaults as the prime suspect in its investigation of a University employee's rape and murder.
The Ann Arbor Police Department linked the incident to three earlier cases through DNA testing at the Michigan State Police Crime Laboratory in Northville, Mich.
The serial rapist case ended with a guilty verdict for 33-year-old Ervin Mitchell Jr. in June 1995. The man was tried for three counts of criminal sexual conduct and one count of attempted murder.
From 1993-94, a University student was attacked and a University employee was killed.
Overall, police suspect the serial rapist was responsible for 11-12 assaults. The first case dated back to Sept. 28, 1992.
In the fourth incident, Christine Galbraith, who worked in the Undergraduate Admissions Office, had cut through a wooded area to return home on Saturday, May 7, 1994. She was attacked in the 2100 block of West Stadium Boulevard, near the south side of the Farmer Jack parking lot.
The case gained intensity with another rape of a local woman on Oct. 13, 1994, near Community High School. The 41-year-old Ann Arbor woman was the first victim to get a good look at her attacker.
"You knew about the incidents. You knew there was a serial rapist around," said LSA senior Marc Gilman. "It heightened their awareness."
The guilty verdict not only ended the trial of the serial rapist, but quenched the fears of many local women. Joyce Wright, SAPAC'S prevention education coordinator, warned at the time of the verdict that the danger was not entirely erased, and people still need to be careful.
"There is a sense of relief that the trial has come to a conclusion and that the person is off the streets," said Wright in a June 28, 1995, article in The Michigan Daily. "Even in light of this you need to be aware."
KRISTIN SCHAFER/Daily
Safewalk volunteers Aaron Kaufman and Stephanie Herzberg walk LSA sophomore Laura Westberg through Ann Arbor to ensure she gets home safely.
KRISTEN SCHAEFER/Daily
Recent graduate Nichole Argyres, one of Safewalk's coordinators, works to increase campus safety.