Howdy! I've been keeping homing pigeons for a year and a half now with good success. I'm about to move to a property where no livestock has ever been, and want to take biosecurity seriously with this move. I've only had 3 mystery pigeon deaths and I wanted to see if anyone here had any thoughts about them. 1st; squab, 1 of 2, died at 4-6 weeks (guesstimate?). Between 2 nests I had 4 squabs of the same age. The other 3 were up, walking, and badgering the parents for milk. This squab never got up or walked. This nest was extra filthy, I cleaned it a couple times but holy smokes these two squabs were covered in feces despite my efforts. The parents picked a very small hidey-hole to rear them in... Anyways, this squab died without ever getting up or leaving the nest. I did not do a necropsy, assuming contaminations/exposure was the cause. 2nd; the sibling of the above squab. Survived to 3-4 months of age, never flew though. Started favoring 1 leg as an adult. Lived on the ground and mostly ate and drank unenthusiastically. Developed diarrhea and I eventually put it down. It was a decent weight, not quite as fat as the others I butchered at the time. Nothing out of place in the organs. I don't recall exactly how its liver looked, but it wasn't anything so freaky it stood out in my mind. Possibly signs of fighting infection, but no tumors, lesions, etc. Squab was covered in feces and had loads of mites (which I have NEVER seen on any other pigeon I've handled, dead or alive) 3rd; mother of those two squabs. Age unknown, got her as an adult, but her nose/beak bumps (? still don't know what they're called and haven't found info on them!) were HUGE, unlike any of my other pigeons. I thought maybe this could mean she was very old, but that's just a shot in the dark. She lived over 1 year with me, but did die this winter. In January I noticed she always seemed to be on the ground. I eventually deduced that she had stopped flying altogether. I would put her on a roost (they live in a large outdoor run with 6.5' roof) and she'd topple off of it like her wings didn't work anymore. I wasn't sure what was going on so I let her be. She maintained a good weight and ate normally from the ground, but eventually died with really bad diarrhea. Nothing in her organs stood out to me, she was a good weight, and I didn't notice any mites on her body. Edit: The mother and her squabs both displayed inability to use legs and/or wings. This was her last brood before death. However, I have breeding adults that are her offspring (+same father) who have displayed no signs of illness. I have no idea why these three died. I thought "marek's" due to one never standing up, one not using a leg and another stopping flight. But from what little I can find, marek's doesn't infect pigeons? I can't find much on pigeons illnesses and diseases otherwise/ I've had in excess of 16 birds at one point, but try to maintain 2-4 breeding pairs. My founding stock came from an auction as 2 different lots of birds. I mark breeding groups and have not had any in-bred pairs yet. Anyways, I've not had another pigeons get sick or die on me yet. It's been 2 months since the last girl died and my flock seems just fine. But these three deaths put my hackles up. Any thoughts or opinions from pigeon keepers out there?