Free Fifty Degrees Below by Kim Stanley Robinson

open air. Across the ravine was a steep wall of green. Here the sound of the creek was louder than the sound of the city. If Beach Drive stayed closed to traffic, as it looked like it would, then water would remain the loudest sound here, followed by insects. Some birds were audible. The squirrels had gray fluffy backs, and stomachs covered with much finer fur, the same gold-copper color as the lion tamarins still missing from the zoo.
    There were lots of deer, white-tailed in name and fact, big-eared, quick through the trees. It was a trick to move quietly through the forest after them, because small branches were everywhere underfoot, ready to snap in the mud. People were easier to track than deer. The windrows were the only good place to hide; the big tree trunks were broad enough to hide behind, but then you had to look around them to see, exposing yourself to view.
    What would the forest look like in the autumn? What would it look like in winter? How many of the feral animals could survive a winter out?

    IT TURNED OUT THAT HOME DEPOT sold a pretty good treehouse kit. Its heavy-duty hardware allowed one to collar several floor beams securely to trunk or major branches, and after that it was a simple matter of two-by-fours and plywood, cut to whatever dimensions one wanted. The rest of the kit consisted mostly of fripperies, the gingerbread fill making a Swiss Family allusion that caused Frank to smile, remembering his own childhood dreams: he had always wanted a treehouse. But these days he wanted it simple.
    Getting that was complicated. For a while he left work as early as he could and drove to one edge of the park or another, testing routes and parking places. Then it was off into the park on foot, using a Potomac Appalachian Trail Club map to learn it. He hiked all the trails that had survived, but usually these were just jumping-off points for rambles in the forest and scrambles in the gorge.
    At first he could not find a tree he liked. He had wanted an evergreen, preferably in a stand of other evergreens. But almost every tree in Rock Creek Park was deciduous. Beech, oak, sycamore, ash, poplar, maple—he couldn’t even tell which was which. All of them had tall straight trunks, with first branches very high, and crowns of foliage above that. Their bark had different textures, however, and by that sign—bark corrugated in a vertical diamond pattern—he decided that the best trees were probably chestnut oaks.
    There were many of these upstream from site 21. One of them canted out and overhung the creek. It looked as if its upper branches would have a nice view, but until he climbed it he wouldn’t know.
    While making his reconnaissances he often ran into the frisbee golfers, and when he did he usually joined them. In running the course they always passed site 21, and if the homeless guys were there the second vet, whose name was Andy, would shout his abrasive welcome: “Who’s
winning
? Who’s
winning
?” The frisbee players usually stopped to chat for a moment. Spencer, the player with the dreadlocks, would ask what had happened lately, and sometimes get an earful in response. Then they were off again, Spencer in the lead, dreadlocks flying under bandanna, Robin and Robert following at speed. Robin sounded like some kind of deist or animist, everything was alive to him, and after his throws he always shouted instructions to his frisbee or begged for help from the trees. Robert spoke more in the style of a sports announcer commenting on the play. Spencer spoke only in shrieks and howls, some kind of shaman language; but he was the one who chatted with the homeless guys.
    During one of these pass-bys Frank saw that Chessman was there, and under Zeno’s baleful eye he offered to come back and play him for money. Chessman nodded, looking pleased.
    So after the run Frank returned, toting a pizza in a box and a sixpack of Pabst. “Hey the doctor’s here,” Zeno said in his heavy joking tone. Frank ignored