I am very keen to attract postdoctoral researchers in mathematical biology. There are several ways to obtain funding for a postdoctoral position in mathematical biology at McMaster:
The Mathematical Biology Group normally has at least one postdoctoral fellowship available each year. See Postdoctoral Fellowships in Mathematical Biology.
If you are a Canadian citizen or landed immigrant then you are strongly encouraged to apply for an NSERC postdoctoral fellowship.
In years that it is available, you can apply for the E.B. Eastburn Postdoctoral Fellowship.
You can also apply to The Fields Institute for Research in Mathematical Sciences for either the Jerrold E. Marsden Distinguished Postdoctoral Fellowship or a Thematic Program Postdoctoral Fellowship in years when there is a theme associated with mathematical biology. The Human Frontier Science Program offers long term and cross disciplinary fellowships. The Life Sciences Research Foundation offers fellowships in all areas of the life sciences.
US citizens can apply for a Fulbright Scholar Award.
Citizens in the UK or other Commonwealth countries can apply for a Research Fellowship from the Royal Commision for the Exhibition of 1851. The Government of Canada also has available The Canadian Commonwealth Scholarship Program.
If you are computationally oriented then it may be possible to obtain postdoctoral funding through SHARC-Net.