Dave Hallock, Eldora. Spring has had a hard time getting going this year. It was doing good in June, until this past weekend when snow returned. There was abundant moisture throughout the West this winter and spring, which influenced when various species returned as well as what returned. It might also influence the nesting success of some birds.

The wet May kept a lot of migratory birds at lower elevations. There were numerous reports of colorful Western Tanagers around people’s homes in Boulder, Longmont, and places in between. It is likely they were waiting for the weather to get nicer on their breeding grounds in the mountains.

The late Dr. Bob Cohen studied Tree Swallows in western Boulder and Gilpin counties for 40 years. He once told me an interesting finding. Banded birds he had seen in the mountains were seen later that same day at Walden Ponds east of Boulder. In the spring when the weather is highly variable, the swallows would come up to the mountains during the day and then retreat in the evening until the weather becomes more conducive to nesting. It is likely other avian species, particularly neotropical migrants, follow a similar pattern and delay the commencement of nesting activities until better weather.

Birds that nest on the tundra, in the krummholz (the stunted trees just below the tundra), or in the spruce-fir forests of the subalpine are likely to start breeding very late this year. White-crowned Sparrows, whose favorite nesting habitat is the krummholz, have been present in the Nederland area all spring in large numbers, as they wait for the snow to melt on their nesting grounds. The impacts of a late snowpack on numbers of birds often shows up the following year due to poor nesting success. And there is evidence that a late snowpack results in poorer avian nesting success. A fifteen-year study of the nesting biology of Dusky Flycatchers in the high elevations of the central Sierra Nevada of California (they also nest here) 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. So, the impacts of this year’s snowpack on the numbers of birds may not be seen until next year.

The recent cold and snowy weather saw a reappearance of high elevation birds at local feeders. Flocks of Brown-capped Rosy-Finches, who nest in the rock crevices above treeline, have recently been seen in the Nederland area. And White-crowned Sparrows are back, driven out of the krummholz by the weather (thanks to Susan Wagner for the report). It is not going to be a good year for nesting high elevation birds. Dr. Bob Cohen found that for many high elevation birds, cold and damp weather had a greater negative impact on nesting success than drought. The adults could not get enough food to the newly-hatched young to keep their energy up and fight off nest parasites and other diseases that are often present.

It has already been a good year for some butterfly species. Painted Ladies (orange with black wing-tips, and scattered white and black spots or patches) had a large migration from the desert southwest and were being seen in large numbers in Boulder County in April. These large migrations seem to be triggered by El Niño weather events, which produce abundant moisture in the southwest deserts, followed by prolific blooms of desert annual wildflowers that provide the fuel for the butterflies. Red Admirals (dark bodies with reddish-orange bands and white spots near tips of wings) were also abundant this spring.

Looking ahead, July is one of the best months to observe nature in the Nederland area. It can be a good month for wildflowers, though many blooms are running late this year. The yellows of sulphur flower and rose-purples of Lambert’s locoweed can dominate montane meadows in early July. Alpine meadows are at their peak; the showy yellow sunflower old-man-of-the-mountain is the most conspicuous. The native cool season grasses Parry’s oatgrass and Thurber fescue are green, tall and full of seeds in montane and subalpine meadows.

With the flowers come the butterflies. Look for the large Weidemeyer’s Admiral (mostly black with white markings) around willows and aspen, Parnassians (mostly white with black and red markings) around stonecrops, and Meade’s Sulphurs (burnt-orange and green) in the alpine meadows. Many different types of diminutive “blues” will be found around mud puddles.

Mammals show a mixture of activity. Elk have mostly completed calving and the herds regroup at higher elevations. Pine squirrels and chipmunks are having their young. Pikas are already getting ready for winter in the alpine talus slopes as they begin cutting plants and building their hay piles. Long-tailed weasels breed (July/August).

Birds are quieter this month than in June, as they spend more time incubating and feeding young. Male Rufous Hummingbirds arrive from the north (a few may make it back by the end of June) and begin competing with our local Broad-tailed hummers for feeders.

(Originally published in the June 27, 2019, print edition of The Mountain-Ear.)