I have heard it is pretty common for stray cats and kittens to do this, thankful you managed to rescue her! I went to a mechanic once in the winter when I was having car trouble and sadly there had been a mouse nest in my engine (I lived at a farmhouse for a time in college). These creatures do need help in the winter. I feed the birds, it's all we have in our city garden but it is amazing how much happiness it brought me during Covid lockdowns in the UK. Thanks for looking after all of your local critters!