The Birds did migrate to Utah in 1850, but the William Bird that traveled with them was only 5 years old. Source for birth date taken from Nauvoo Land & Records (Mormon Battalion) & Hist of Church Vol 5 page 349..
Born in Southport, Chemung, New York
1823 July 18
enjamin Freeman Bird
1839 September 13 (Age 16)
Residence When Called
1894 April 18 (Age 70)
Willaim Bird (1823 - 1894) Profile