MILTON -- Twice a week, the ''foliage king" surveys his kingdom, checking up on the bellwether sugar maple just outside the Blue Hills Reservation, circling swampy Fowl Meadow where trees change colors first, and cycling up to the top of Great Blue, where he'll spot the bright orange, yellow, and red splotches rippling over the green hillsides.
From atop Great Blue, Dave Furey -- a Blue Hills park ranger given the weighty responsibility of telling the rest of us where and when the local color is peaking -- gauges just how the foliage season is progressing and how many days are left in the fall display, and then prepares a report for the Massachusetts Office of Travel and Tourism to help guide visitors to the best fall color in the 7,000-acre reservation.
Finding the best place to spot leaves can be ''like choosing a movie in a city of a thousand theaters," said Furey, who was given his nickname when he got the job.
The trees in the Blue Hills have just begun to blush -- the color delayed, the thinking goes, by the unusually warm fall weather -- with the official status still hovering in the ''early" foliage range. Traditionally the local peak comes in mid-October, according to rangers, when leaves shed the chlorophyll-induced greens of summer and show their true underlying colors.
Throughout Plymouth and Bristol counties, things have been going a little slower than in the Blue Hills, even for the red maple, sumac, shrubs, and vines that tend to turn first. But Joe Perry Jr., a state forester and the chief leaf monitor for Southeastern Massachusetts, said that once the change starts in earnest, it happens very quickly.
''All of a sudden, it's like a snap. A couple of days and it's -- wow -- it's like they just changed overnight," Perry said.
The data collected by leaf monitors from across the state show a normal foliage pattern so far: the most change in the higher altitudes of the Berkshires, while the Pioneer Valley, lower Worcester County, and finally the area south of Boston follow suit.
''We've had an unseasonably warm September, and I think that's going to help extend the foliage season. Although we need those cold nights to give the memo to the leaves that it's time to go," said Amy Strack, director of marketing and communication for the state tourism office. It makes the reports available to visitors from near and far, fielding some inquiries from as far away as Europe.
Predicting the color display is a game of chance: a freak wind storm or a hard frost could shorten the season in one unpredictable punch, and the brilliance of the show hinges on everything from minerals in the soil to summer rainfall to tree pests.
''It's so not a science . . . there are so many variables, and everything changes every year," Furey said of his daunting task: to climb to the highest point in the park and turn blotches of color into mathematical estimates of just how many of the hundreds of trees spread out in every direction have changed. After consulting with foresters and other leaf monitors across the state, he said, he resigned himself to just eyeballing the forest to come up with a percentage, with some days -- ''I'm feeling pretty confident it's 5 percent" he said one recent afternoon -- more certain than others.
But Furey knows that revenue from tourism during the fall helps fuel the state's economy, and he goes the extra mile in his reports, moving through the park by car or bike looking for little pockets of trees that are showing color and suggesting hot spots for foliage paddles or hikes for those looking for early color.
''We kind of own the Boston market because it's so convenient for so many people," Furey said of the Blue Hills expanse. But behind his love for the park is an egalitarian ethos: ''We're trying to get people out here, to create revenue through tourism, but I don't feel I'm competing to bring people here as opposed to Myles Standish Forest."
Even if they are a little behind their usual cues, he said, the trees south of Boston will soon begin the foliage show, shedding the green in their leaves through a natural process. They wean their leaves of water by forming an abscission, a kind of tourniquet that seals off the leaf from the rest of the tree. Chlorophyll production stops, and the leaves lose their green pigment, revealing their true colors.
''It's like shedding a blanket or a bed sheet. You pull away the covers, and the red, yellow, or orange" that are the leaves' underlying colors finally appear.
Oak leaves have a brownish tinge. Red maple, the signature tree of Southeastern Massachusetts, turns a brilliant red. Beech leaves, which tend to loiter at the end of foliage season, are yellow underneath their chlorophyll cloaks.
Leaf color also depends on the local conditions, the minerals in the soil, and the individual tree's genetics: ''Not all maples are the same, just like not all Irishmen are the same," Furey said. But this year, foresters are worried about the foliage colors because a number of stands of trees have been stressed, both by the dry summer and an upswing in caterpillars.
''I actually think fall foliage this year [could suffer] because there's lots of dead oak trees totally defoliated in parts of Freetown, even driving up Route 3," said Perry, who has seen how trees weakened by the winter moth, tent, and gypsy moth caterpillars will simply skip their brilliant fall palette, turn brown, and shed leaves.
But Perry said he is still looking forward to scenic drives on Route 3, or on his favorite route, Interstate 495 through Middleborough and Norton, then back on Route 123 to get some ''local flavor."
The foliage king is hopeful that even with the caterpillars, the area south of Boston will soon be blazing everywhere in a spectacular show: ''Unusually warm weather is pushing our peak viewing time back," he wrote in a recent report. But he foresaw brightly colored trees and trails over the next few weeks.
''Just to go and observe and enjoy it," he said. ''It's kind of like going to a museum."
To get biweekly foliage updates from around the state, or suggested travel routes for the best leaf-peeping, visit www.massvacation.com, or call 800-227-MASS. Carolyn Y. Johnson can be reached at email@example.com.