Oh yes yes, that makes perfect sense now that you mention decomposition, duh. Here I am, a nurse, a Psych Nurse to boot, and you'd figure Id know, but not till you throw the RN slang into it, then I get it. Yes, the birds are relatively small to human body per say so rate of decomposition may be quicker, especially when given all of the exterior factors, heat, humidity, time of day, geographic location- literally, higher elevations take a little longer than closer to sea level, I think it has to do with the exchange of Oxygen in the air.
Im going to have to research the SGD, never seen one, in person or otherwise, until you showed your babies!