chirping

Question
Hello. I had a pair of rats just over a year old. This past week one passed away with no
apparent signs of illness. They had always made a sound which based on others' questions
would be best described as a "chirp". They chirped every once in a while at times when they
seemed content (eating, snuggling with each other) so I did not think that it was a bad thing.
I assumed they were just chatty. They were active, had bright, clear eyes, nice coats and very
healthy appetite. After reading I am concerned that perhaps the occasional chirp was a bad
sign? The lone rat still makes the chirping noise on occasion. Is he just stressed out over the
loss? I do not want to bring him to the vet unless it seems warranted because I really do not
want to stress him out more. Also, should I be looking into getting him a new companion? Or
will this stress him out more? And if I do, should I get a younger rat or one his age? Thank  
you for any advice.  

Answer
Hi Chelsea

For starters, I am going to assume you know what bruxing means. This is when they grind their teeth really fast and it is like a clicking sound. Sometimes their eyes vibrate too. This is called boggling. Rats do this most often when content and happy but they can do it when angry or sick (the bruxing, not the eye boggling) but that is pretty rare.  Usually its done when they are happy. the only sound you will hear is the clicking of their teeth grinding together.
The chirping....when they do this, do you look at them to see what they are doing?  Are they usually sitting in one place and perhaps moving in a rythmic fashion, almost like they are having spasms? often rats will have hiccups and they make this chirping noise when they do this. It lasts for just a minute or two usually.  This is normal and not to worry about.  If you hear congestion in their chest and nose, that is when to see a contact  vet.

As for the lone rat being stressed: Some rats are ok after the loss of their cagemate and others do get depressed. This stress can indeed cause the immune system to crash and the rat may become ill. I have had my rats become sick and even pass away a few months after losing their cagemate and it is linked to stress. Right now I just lost my wonderful buck and his brother is all alone now. he seems just fine and happy but I may still get him another friend. I have three other rats at home but one is totally blind and lives alone the the other two are grumpy old men that are 2.5 years old and would not welcome Santana into their mischief.  
I would consider another cagemate for him a bit younger than he is  and in fact, I often suggest two younger rats so this way they can play and wrestle and do rattie things that youngsters do without annoying the older rat but that is entirely your choice. I do feel another friend would be ok though. I would just take it slow, do proper quarantine and introduce them slowly and they should become friends just fine.

Anyhow, back to the chirping....I am pretty sure what your hearing is hiccups so if you can let me know if that is what they seem to be as per your observations.