I do think that some animals ARE aware if their loved ones are dying or dead...
My uncle used to come up from Florida to visit us every summer for a few months...
Well, he had been very sick with cancer but was in recovery..
He had also just lost his loved Golden Retriever before he came up to vist us one summer...
I ,at the time, had a young border collie mix dog, Willow... and my uncle and her fell in love with each other during the months that he stayed with us.
So i asked my uncle if he would like to take her back home with him, because i KNEW it was what he needed.
Of course, it killed me inside, but i kept it hidden.
When he left he took her and they had a few very happy years together, where that dog bonded to him like nothing i have ever seen.
His cancer came back and when he was very ill in bed dying, Willow would lie in bed with him and give him comfort, she did NOT want to leave his side.
As he grew sicker, she became more frantic, and would now growl at people who tried to approach the bed to care for him.
Finally they HAD to put her in a crate the last day he was alive, because they were afriad of getting bit. And this dog was NOT a biter, she was VERY human friendly and trained. But i think she thought they were "hurting" him..
I WISH i could have been there at the time... i would have let that dog stay with him.
My other Uncle said that Willow KNEW when he died... because she started to howl and whine... it amazed everyone there to see it. And they still talk about it sometimes whenever my uncle comes up in family conversation..
Another one,
When MY dog Duke was dying one night..(i didnt know it..i just thought he was ill and was going to bring him to the vet early the next morning when they opened.. he had been vomiting earlier that day.. etc..)
Anyways, My 2 dogs Duke & Daisy Mae were so close..they grew up together and ate, slept, played, did EVERYTHING together..
Well that night that he was so ill, Daisy kept barking ALL night long.... on and on... so i would get up and check on them both... She was pacing and upset. But i just didnt understand WHAT she was telling me.
Like i said i knew he was ill, but not deathly ill, i just thought he was sleeping soundly and so i didnt wake him up.... just kept getting up during the night and making sure he was "okay"...
Well, Daisy KNEW something that i didnt... and she TRIED to tell us.
The next morning, we got up and checkd him again, and then i saw how ill he was, he was finally awake but he could not stand... his heart stopped just as we pulled into the vets parking lot. They tried to bring him back, but they couldnt.
Soo.. YES, i FIRMLY believe that dogs DO know when their loved ones, or members of their "pack" are really ill or passing away... and they DO respond to it.
And yes, some do mourn the loss, my Daisy SURELY did for a long while.