When will the first robin reach the end of the road?

Location of Shageluk, Alaska

Year
First Robin in Shageluk, AK
1997 April 20
1998 April 16
1999 April 27
2000 April 21
2001 May 8 (heard May 2)
2002 April 25 (heard Apr. 17)
2003 April 24
2004 April 23
2005 April 9
2006
April 23
2007 April 22 (heard Apr. 20)
2008 April 21
2009 April 25
2010 April 26
2011 May 1
2012 ????

Records of first robins

Predict
When do you predict the students at latitude 64N in Shageluk, Alaska, will see their first robin? Use the records students have kept since spring 1997 to make your prediction.