Dave Hallock, Eldora.     The ground was full of moisture going into this year's growing season. Last September's heavy rains filled the aquifers. The above-average snowpack on top of this had people worried about potential flooding as spring arrived. The flow in Middle Boulder Creek, at the gauge just before it enters Barker Reservoir, peaked at around 560 cubic feet per second (cfs) on June 1st, which was produced by a combination of rain and snowmelt. But we didn't have real warm days during that period to push the creek higher.

This is almost 100 cfs above last year's peak, but about 100 cfs below the 2011 peak, and well below the all-time recorded high of 811 cfs on June 2, 1914.

The abundant fall moisture and high snowpack meant a couple of things relative to vegetation. First, many plants bloomed later than normal. Aspen leafed out about 1-2 weeks behind their normal time. Second, there was lush vegetative growth this year. When blooms occurred, they were generally tall and abundant. Currently, Porter aster and showy golden-eye are painting the meadows.

But butterflies appeared to respond to the moisture in the opposite direction, despite the plentiful flowers. Numbers of many species appeared lower than normal. Last September's rain could have played a role. By fall, many of our local butterfly species are in a resting stage that lasts through winter, and are often located near ground level, such as on a blade of grass. The protective covering in the resting state, referred to as a chrysalis, can generally make it through rain and snow. But a rain of that magnitude, with lots of sheet washing and large puddles, may have led to greater mortality than usual.

Bird numbers were also down this summer, as evidenced by the final tallies on the 33rd Indian Peaks Breeding Bird Count. Low numbers were seen for many of our more common species, including mountain chickadee, ruby-crowned kinglet, American robin, and yellow-rumped warbler.

The low numbers were more pronounced in the montane count areas than the subalpine.  Other species with lower than average numbers included green-winged teal, mourning dove, olive-sided flycatcher, warbling vireo, red-breasted nuthatch, Townsend's solitaire, hermit thrush, Wilson's warbler, Western tanager, and Lincoln's sparrow.

This is the third summer in a row with lower than average bird numbers. The previous nine years saw above average numbers. Why the decline? Many factors can influence the population cycles of birds. Last September's rain caused avian mortality, as evidenced by the dead birds people found, particularly in the foothills and plains.

But did it cause mortality to the birds that nest here? Certainly some could have been down there, as some of our breeding species do a vertical migration to the foothills for winter, and some neotropical migrants also head down before moving south. And it is not like the extended period of rain made it easy for the birds still here.

There is evidence that a late snowpack results in poorer avian nesting success. Maria Pereyra has studied the nesting biology of dusky flycatchers, a species that also nest here, in the high elevations of the central Sierra Nevada of California for 15 years. She found that in years of light snowpack, nesting birds that laid eggs by mid-June successfully fledged more young than during years with a late snowpack.

Then there is the influence of the timing of weather events during the nesting season. There is evidence that high elevation birds are less successful fledging young from the nest when there are extended periods of cool and rainy weather. This adverse weather  makes it more difficult for the adults to get enough food to the nestlings: it is more difficult to find food and the young need more to meet their energy requirements.

The month of July during the years 2011-2013 each saw abundant monsoon rains, in the vicinity of 7 inches of precipitation. Could this be a reason for the lower than normal avian numbers during the summers of 2012-2014?

This influence of cool and rainy weather on the success of breeding birds was one of things I learned from talking with the late Dr. Bob Cohen, who passed away this past spring. You may know him as the "tree swallow guy," the one tending all those bird boxes throughout the mountains of Boulder and Gilpin counties. He studied the breeding ecology of tree swallows for around 40 years.

Someone that has specialized in their field for that long has amazing insight to subtle details. He saw that the swallows at higher elevation were more limited by cold and rain, while those at lower elevation saw heat and drought as some of their limiting factors to finding enough food for nestlings.

September in Peak to Peak

Following are some of the September nature happenings in the Nederland area. I call this the time of “dropping cones and shedding needles.” Squirrels are dropping pine cones to the ground for winter reserves to be stashed in their middens. Needles on many conifers will start turning brown, particularly in lower branches and the inner portions of other branches, as the trees shed excess foliage. Of course, if you see all the needles turning brown, you may have a larger problem.

Berries continue to ripen. Look for huckleberries, chokecherries, raspberries, and others. If you hit a good patch of huckleberries, you can smell their wonderful aroma in the air. Black bear diets heavily shift toward berries as they gorge themselves for winter hibernation.

Bull elk are bugling. The peak of the rut occurs around the end of September. Moose also start having other things on their mind, as breeding begins around mid-September and runs until early November.

Pocket gophers will continue to aerate the ground by tunneling and leaving mounds of dirt on the surface.

Birds are on the move. Flocks of sparrows, warblers and bluebirds are coming from the north, while local birds are flocking up and getting ready to head south. The tundra is a good place to see migrating birds that are feeding on abundant grasshopper and cricket populations. Raptors, including red-tailed hawks, golden eagles, northern harriers, American kestrels, peregrine falcons, and prairie falcons frequent the tundra during fall migration.

A few butterflies will still be around in September. Some of these, like commas (orange with black spots and angular wings) and mourning cloaks (large, dark brown with yellow stripes), will overwinter as adults and can emerge during warm periods in winter or in early spring. While not much is known about painted ladies (orange with black and white markings) migrating south, some are often seen in September and October in high-elevation meadows making a strong southwest movement.