View From The Shed by Volunteer Shaun - GONE BUT NOT FORGOTTEN

GONE BUT NOT FORGOTTEN

Last week I used this blog to celebrate The Next Generation, in which I spoke about how many of Old Moor’s star species have reproduced again this year. Looking back at these Views From The Shed, I’ve also written several articles examining various stages of a bird’s life and how their senses and body parts differ quite substantially from our own.

If I’m fascinated by a bird’s birth and subsequent life, then it’s only fitting that I should share a similar interest in that same bird’s death; how they go about the process of dying and what happens to them afterwards. I understand that some of you might find this subject a little strange and morbid. That’s fine, feel free to skip this one and come back next week when I’m sure that the usual levels of information and silliness will be resumed. But I feel it would be remiss of me to ignore this most important and final stage of a bird’s life, and what happens afterwards.  

Let’s start with how birds die.

A predator will rarely target a healthy bird. Trying to catch a bird that is in the peak of fitness will frankly be too much like hard work for it. So the hunter will always go for a bird that appears less likely to escape. This could be through youth, inexperience, illness, injury or simple old age. As a bird gets older its chances of illness and injury naturally increase and therefore so do its chances of becoming a tasty meal. A prey species has to be in tip-top condition to avoid being taken by a predator. It’s an occupational hazard that many will eventually fall victim to.

There are of course exceptions. Some songbirds will evade capture well into adulthood but eventually old age catches up with them and they start to feel the cold more, they don’t handle the rain as well as they used to and they find it hard to defend a territory against the younger, stronger versions of their kind. So they will hide away from the predators instead of running from them. They’ll take themselves off into a secluded, enclosed spot and try to ‘sleep off’ their aches and pains. And inevitably some of them simply won’t wake up.

And then….

I’m not going to get all theological or philosophical here. Those are areas where we all have to find our own paths. You can decide for yourself what happens to the bird’s spirit, ghost, soul, whatever - if it even has one - but I am going to discuss what happens to the bird physically after death, and it’s much stranger than I expected.

The first thing to consider is that a dead bird might be picked up by a scavenger. These birds and animals are the rubbish collectors of the natural world and we’d be knee deep in rotting carcasses without them. But sometimes a body lies in a place that’s difficult or dangerous for a scavenger to get to. In this case the corpse will immediately begin decomposing and, especially where small birds are concerned, this happens shockingly quickly.

A mammal the size of a mouse might take around three weeks to decompose down to bare bones. Scale that up to something like the corpse of a fox and the breakdown of all soft tissues, leaving only the skeleton, could take two or three months. Of course, these figures very much depend on the weather, general climate and location - for example if the body is dry, cold, covered or in shade etc. 

Mammals are primarily made up of large muscles, strong and heavy bones, fats, proteins and a thick layer of skin and fur. Consuming these is very useful for other creatures to build up their own healthy bones and muscles.

Birds’ bodies are very different though. They aren’t just like flying mammals - that would be bats. Remove the feathers and the physical body of a bird is mostly composed of very small muscles, air sacs, very light and hollow bones and some paper-thin skin. They can’t afford to carry any fat or spare weight at all.

These bird/mammal differences are reflected in the time it takes for the decomposition process to complete. While a mammal can take several weeks or even months to skeletonise, a small bird can be almost totally gone within a matter of days, including the bones. The last thing you might find could be a small group of feathers, the most difficult part of a bird to break down at a microbiological level.

Bacteria, fungi and insect larvae all move in and go about their grisly business almost as soon as the bird dies. These mini- and micro-beasts will easily devour every part of the delicate bird much more easily than a tough mammal. Pretty soon there’s nothing recognisable to the human eye, just an indistinct blob, and even that won’t last long. Within just a couple of days it can have gone from a perfect-but-dead bird to almost nothing. Nature cleans house much more quickly than I do.

Keep in mind that I’m talking about the smaller birds here, pigeon-sized and below. We sometimes see dead Swans or Geese here at Old Moor and their bodies stay around for a week or more, providing food for the scavengers of all sizes here on the reserve. And that’s fine, that’s natural and it’s good to see. It’s how things should be, even if it’s not exactly pretty to our human sensibilities. 

I know that all this talk of death has been a little grim which is why I haven’t included the usual level of daft comments, but it’s important that we don’t ignore death, especially from nature’s point of view. 

I’m going to finish this week’s blog in the same way that I did last week because the two are really two halves of the same story. A bird hatches, a bird lives and breeds, and a bird dies.

And the cycle continues.