How common is it for birds to desert their young when they are still in the nest?

I was lucky enough to have a Songthrush nest in my garden for the second year in a row. All seemed well, she had chosen a secluded spot in a quiet part of the garden, under some ivy over hanging the garden wall . Having not seen any activity for a day or so I investigated further to discover that sadly one chick had fallen from the nest and had not survived. On closer examination of the nest I noticed it was leaning over and that there was no activity, no sign of life. Reluctantly I reached inside only to discover the rest of the brood was cold. One by one I removed a further 4 chicks sadly all were dead. Is it fair to assume that the mother desrted the nest when it tipped over. The chicks were quite well advanced , about 2 to 3 inches long, well fed with some feathers. I straightened up the nest and managed to support it with some twigs in the vein hope that she might return. Clearly all her hard work had been for nothing. No doubt she will be starting the process all over again in a more suitable place.