The graph above shows the mean average lifespan for each birth year for all the rats who have lived here.
2006 was an awful year in which I took on all the males from a rescue litter, who all had respiratory problems for most of their short lives. This was the litter which prompted me to begin breeding to try to extend lifespan, as it was so heartbreaking to lose them so young.
2007 was a very good year where most of my rats originated from breeders and lived good long lives.
2008 was the year of my first litter, but most of my rats were still sourced from other breeders.
2009 was an improvement on the lifespan but was more likely luck than anything else.
2010 looked as if it would be a poor year due to more rescue rats, in particular Hope and Tinkerbell who lived only 5 months and 9 months respectively, but thanks to Rowan living well over 3 years it came out only a little below average.
This graph shows the percentage of rats that are still alive at a given age.
Other Breeder Sourced - rats from other breeders that I've brought in to Ratty Corner either as pets or to breed from. These usually have an exact birth date and come in as kittens under 13 weeks. They tend to come in around the UK average level.
Baby Non-Breeder - rats under 13 weeks old, generally from rescue litters and usually with an exact birth date or very close estimate. These have a fairly poor lifespan, although some do reach an impressively old age.
Adult Non-Breeder - rats over 13 weeks old, generally rehomes but occasionally rescues. Generally with a very rough estimate of their age and usually over 12 months, hence the low number of younger deaths.
Brandywine Stud - rats bred by myself, or occasionally rats bred by others but with both parents bred by me. These all have exact birth dates. These are showing a fairly high number still alive at 24 months, but with a rapid fall off for which I'm unable to account. There may be a slight advantage from having stayed with me all of their lives and therefore never having the stress of being rehomed.
All at Ratty Corner - all of the above categories combined.
UK Average - taken from my rat lifespan survey, so comprising a self selected sample of owners who visit my site.
My hope is to raise both the average and the maximum lifespan. The textbooks say that it is more difficult to raise the maximum, but it should be possible to make the graph squarer by raising the average.