The browse bar is a beam on load cells that the giraffes pull leaves from, and it logs every pull by weight and by height along the bar, so we know who is eating and how much. The tallest animal we have reaches four point six metres. Every night the bar logs pulls at five point four, and the browse at that height is stripped by morning.
I am the hoofstock keeper responsible for the giraffe house, and the browse bar is the one bit of instrumentation in it.
How the bar works.
Browse, which is cut branches, is hung along a horizontal beam that runs the length of the house at a height the animals have to stretch for, because stretching is good for them. The beam sits on load cells and has sensors along it, so each pull is logged with its force, its position and, from the position and the beam's slope, its height.
The animals have their own heights and their own places, and the log is a map of who ate where. The bull reaches four point six metres at full stretch, and the log has never shown a pull above that in the day, because nothing here can reach above that.
Every night, between one and four, the bar logs pulls at five point four metres.
The beam is stepped at the far end, higher, where the house was built for a bigger species in the 1960s, and browse is hung there because it is a place to hang it, and it has never been reached.
It is stripped by morning. The branches at five point four are bare, and the pulls in the log that stripped them are heavier than the bull's, and there are perhaps forty of them a night.
Five point four metres is a giraffe that is not a giraffe we have. It is the reach of the biggest bull of the biggest subspecies, and we have never kept one, and the house has not had a bull that size since the one it was built for, who is on the wall in a photograph from 1968, standing under that end of the beam, reaching it.
What has been checked.
The cells and the sensors, serviced, and the beam's height at the far end surveyed with a laser.
The animals. Four, on camera all night, asleep or standing at their own end, none of them near the far end, none of them five point four metres tall.
The browse. Cut by us, hung by us, and stripped in the way a giraffe strips a branch, from the tip, with the tongue, which leaves a particular ragged end that I have looked at a thousand times, and which is on every branch at the far end in the morning.
The floor. There is sand at that end of the house, and in the morning there are prints in it, under the high beam, big, and the dung that goes with a night's feeding, which the vet has looked at and says is a giraffe's, from a large animal on a diet of the browse we cut.
What the four do.
They do not go to that end at night. In the day they use the whole house, and at night they stay at the near end, together, and the cameras show them standing, at about one, and looking down the house, all four, at the far end, in the dark, and staying like that for as long as the log shows pulls.
They know what is at the end of the house and they are giving it room.
What is done about it.
I hang browse at the far end every day, at five point four, where nothing can reach it, because if I do not it is the near end that gets stripped in the night, from four point six down, by something that pulls harder than the bull, and the four are unsettled in the morning and will not go to the near beam.
The browse budget has a line for it. It is called enrichment, high level, and it is true.
What I do.
I keep the giraffes.
The one thing I have changed is that I hang the high browse before dusk and not after, because in the first winter I was up the ladder at the far end at about half past four in the dark with a branch in my hands, reaching for the high beam, and something took it out of my hands from above, with a pull I felt in my shoulders, and the load cell logged it, at five point four metres, at a force I have not seen since, and the branch was stripped when I found it on the sand in the morning.