In January 2014 during the evening, a captive bred juvenile Psammophis sibilans, about 4 months old, swallowed another, slightly smaller one. The swallowed animal was when I saw it happen, dead but still partly outside the predator. This remained so during the night and the following day. In the evening of that day the predator was dead too.
This was the second time I experienced that a small snake in my collection
swallowed another one just as large as it was itself, and died. The first time
was a juvenile Malpolon insignitus that swallowed a Psammophis sibilans young of
the same length. This time the prey was swallowed incompletely too and the
victim was still alive after a length of time. I decided to save it and pulled
it gently out, and indeed did the sibilans survive, but the predator died the
The last pictures show the belly of the victim after some days. The skin seems a little damaged, but that was all.
This could be an indication that swallowing a very large prey is rather dangerous for a snake. We are often confronted with pictures of snakes that swallowed a prey far too large to be comfortable, but it is not always clear if the snake survived the adventure.
Of course I asked others for their experiences. In the wild, swallowing very large prey is quite common, and as far as observers know, it generally is no problem. Yet, there are other cases too. In March 2015 Tyrone James Ping posted a case of the Vine snake: "I got called out to pick up a Vine Snake in Forest Hills, near Hillcrest. It had swallowed a tree agama and was not doing well. It was died trying to regurgitate it. Sadly, this happens fairly often with these snakes" (source).