For more than a year we have had a sika deer hind coming, on a regular basis, to our garden to graze. Last May, the hind had her fawn right next to the house and we were lucky enough to see it within a couple of hours of its birth. In the last fortnight we have seen the deer in the house vicinity every day, and it is likely she has chosen the garden as a nice safe location to bring another fawn into the world.
Sika deer hind with newly born fawn (mid-May 2017).
It wasn't a surprise therefore for me to see the deer outside, only about 1 metre from one of the sitting room windows. What happened next really did surprise me. A great tit landed on the deer's spine and proceeded to hop along it's back, presumably searching for insects[1]. The deer didn't flinch or react in any way. The sika must have realised the tit was there. Great tits, in common with blue tits and coal tits, are accomplished fliers who will readily investigate every nook and cranny to find a meal but this is the first time I have observed one hunting on top of a large mammal. Although, this may be because I haven't often observed sika deer at close quarters, over an extended period. Spotting a great tit on the spine of a sika deer at several hunded metres distance wouldn't be so easy.
There is an on-going debate as to whether oxpeckers (of the African savannah) have a mutualistic or parasitic relationship with their large mammal hosts, such as zebras or impalas. The oxpeckers are of a benefit to their hosts when they consume insects but there is also evidence that they open wounds to drink blood. Perhaps, the great tits need to be observed more closely to see everything they are up to[2].
Notes
- Update 2018-04-21: I had an extended sighting of the great tit hopping about on the deer's back. I couldn't tell if this was the same bird as previously, but this one was definitely pulling hairs, rather than feeding. The great tit was pulling so much hair that it had the appearance of having a huge mustache. The sika deer still didn't react to this collection activity. The great tit (male) made three separate trips, within the space of 3-4 minutes, to collect the hair. It may still be the case that the great tits are feeding but they are definitely collecting hair.
- Update 2018-04-28: The deer was outside the kitchen window this morning, when the great tit landed on its back. I was able to take some photos of the great tit stripping hair from the deer's back. A crop from one of the photos has been added to this blog post (second photo, above). The great tit didn't appear to be doing any feeding activity and was devoting its time to stripping hair. The bird appeared to be concentrating its efforts in the same areas, leading to near bald patches along the sika deer's back. Although the deer may be moulting anyway, this stripping activity doesn't seem to be a beneficial. As observed before, the deer didn't acknowledge the presence of the great tit.