Mollygo I expect all Christian countries move the Spring Saint Days according to Easter.
Here are the ones I've found out about:
They are only moved if they clash with Holy Week or Eastertide observances.
April:
* April 23: St. George - if it falls within the specific period around Easter.
* April 25: St. Mark the Evangelist - Similar to St. George's Day, if April 25th falls between Palm Sunday and the Second Sunday of Easter inclusive, the Feast of St. Mark is moved to the Tuesday after the Second Sunday of Easter.
* April 29: St. Catherine of Siena
* April 30: St. Pius V
* May 1: St. Joseph the Worker
* May 3: Sts. Philip and James, Apostles
* May 14: St. Matthias, Apostle - the alternative date for St. Matthias is February 24th.
* May 20: St. Bernardine of Siena.
On top of this the exact dates these saints are celebrated can vary slightly between different Christian denominations and their liturgical calendars.
"Moveable feasts" are directly tied to the date of Easter and so shift each year.