We spent a beautiful morning walking along the St. Croix river at Afton State Park recently, and I noticed that it seems more like fall weather now, and a lot less like summer. What a difference a couple of weeks makes in the climate here.
Last year, I posted a look back at some of the best photos of 2013, and thought I might try that again this year. I managed to pare down the initial 63 selected photos of just the MN and CA backyard birds to the top 10 by making some tough choices. Reasons for their selection are listed below the photo, but I would be interested to know if blog readers agree. Which one of these is your favorite?
Oops, I just recounted, and there are 11 birds here. I can’t decide which one to reject, so I’ll leave it up to my readers.
Another lovely plant that I won’t be adding to my garden — Hollyhocks. They seem to be as much of a Japanese beetle magnet as my roses and raspberries.
A sex pheromone is released by females and sensed by a receptor in the male’s antennae to lure them in. But other females can also sense this chemical in the air and are drawn into its source, with the expectation that males will also be there. And so, a mating orgy ensues.
Fall must be like Christmas for Cedar Waxwings and Robins, who gorge themselves on the super-abundance of tree fruits available at this time of year. We found a small flock of adult and juvenile Cedar Waxwings doing just that at the MN Valley National Wildlife Refuge last week.
Learning by trial-and-error which fruits are not only nutritious, but won’t poison you, is a long process; copying what your parents feast on is much easier and safer.
Not all fruits are equal: some plants have co-evolved with fruit-eating birds and mammals that aid in disseminating the plants’ seeds; other plants evolved disseminating mechanisms that involve propelling their seeds through pressure-driven or wind-driven means and protect their valuable offspring with toxic chemicals. In addition, fruits are generally low in caloric value (compared to a nut), and may lack sufficient nitrogen for their consumers’ diets.
So, how does a Cedar Waxwing survive on a fruit diet?
Cedar Waxwings seem to be inordinately fond of high-sugar fruits, and they have exceptionally good absorptive capacity for sugars, not only in their small intestine, but in the proximal part of their colon as well (an unusual place to transport sugar). It is thought that the accelerated sugar transport capacity of their intestine actually enhances amino acid transport as well, because these birds can actually remain in positive nitrogen balance on fruit diets that cause other frugivores (like robins) to lose nitrogen via excretion.
An interesting corollary of this high fruit diet is that cowbirds (brood parasites written about in an earlier post) that lay their eggs in the nests of Cedar Waxwings have doomed their offspring, because cowbird chicks can’t survive on a fruit diet, like the waxwing chicks can.