re
Ganasai,
Piegeons are also birds,especially of the 'satvikam' breed,unlike crows who represent Shanieswarar/Rahu waganaum.So,be happy at least piegeons are eating tarpanam pithru karyam prasadam,you sir are truly blessed.Your pithrus are very happy with your actions,is my take on this.
Brahmanar is one,who is able to have all the satvikam qualities established by Sriman Narayana.Its a lot easier to acheive brahman jnyanam,when established brahminical life is lived,by following various sadhanas.
Regarding eating cows/buffalo/calfs..etc during vedic times this practice was done.Owing to jainism and buddhist influence,himsa of utility animals and other animals got forbidden.Ahimsa took roots very firmly for brahmanas only.So vegetarianism became the rule.
Papam and punyam,is also,based on knowingly doing a action and unknowingly doing an action.Every papam is forgiven by sriman narayanan,if sharanagathi prapthi is continued thru prayer,is my take.Om Shivohum.
gopal.