Sunday, July 02, 2017

July Begins

"One swallow does not make a summer, neither does one fine day; similarly one day or brief time of happiness does not make a person entirely happy."

― Aristotle

"Summer afternoon—summer afternoon; to me those have always been the two most beautiful words in the English language."

― Henry James


Pope Farm Conservancy

July began with beautiful weather and visits to my favorite prairies. In fact, the prairies in the Middleton area are looking about as good as I've ever seen them. All of the wildflower photographs in this post were taken at Pope Farm Conservancy, but the insects were photographed at the creek corridor of Pheasant Branch Conservancy. The Dickcissel is a PFC bird, and the Common Yellowthroat is one of dozens at PBC.


Compass Plant

I continue to be baffled as to why there are so few Dickcissels at the prairie parcel of Pheasant Branch while they're so numerous elsewhere. Is there something not quite right with the habitat? Dickcissels aren't especially shy, so I don't think it's on account of the higher number of visitors on the trails at PBC. Or is it off-leash dogs? It's a mystery to me!


Dickcissel

What is the explanation for all the Dickcissels in Wisconsin this summer? First, let's find out where Dickcissels typically are during June and July. According to Birds of North America, the core breeding range includes grassland regions of se. South Dakota, e. Nebraska, s. Iowa, central and e. Kansas, w. Missouri, w.-central Illinois, central Oklahoma, ne. Texas, e.-central Arkansas, and s. Texas:


Dickcissel Range Map (source: BNA)

The "Breeding (scarce)" area is considered a peripheral range for Dickcissels. This is where they breed most years (lower numbers than core range), but may be absent in others. Within the core and peripheral breeding ranges, there can be seasonal shifts in occurrence and abundance. Before mid-June, the birds are known to nest in the southern areas of the breeding range, and after mid-June there's thought to be northward shift of potential re-nesters.

From Birds of North America:
Occurrence and numbers of breeders in peripheral and sporadically occupied portions of breeding range seem to be correlated with climatic conditions and, hence, food availability in core breeding range (Aldrich 1948b, Mulvihill 1988, Zimmerman 1992). Drought in core breeding range apparently forces many Dickcissels to move outward in search of more favorable conditions for nesting, as, for example, occurred during droughts in 1964, 1973, and 1988 (Emlen and Wiens 1965, Sealy 1976b, Igl 1991). 
Have a look at maps from the US Drought Monitor website:


Drought Map (late June 2017)

Yellow = Abnormally Dry
Light Orange = Moderate Drought
Dark Orange = Severe Drought
Red = Extreme Drought

So, this summer there are serious drought conditions in North Dakota, much of South Dakota, abnormally dry in most of Nebraska, and large parts of Iowa. By far the worst drought is in North Dakota, which is not considered core breeding territory. It's abnormally dry in Nebraska and se. South Dakota, and Iowa, which does cover portions of the core breeding territory.

Things were a bit better last year:


Drought Map (late June 2016)

And back in the summer of 2015 the situation was mostly normal throughout the core and peripheral Dickcissel range:


Drought Map (late June 2015)

Now take a look at June eBird Dickcissel maps:


2017 (June)


2016 (June)


2015 (June)

You can clearly see 2017's substantial density increase in most of Wisconsin and parts of Michigan compared to 2015 and 2016. What I'm wondering is whether these birds went to Nebraska and South Dakota first, and then moved eastward to Wisconsin, or were they northbound birds that diverted northeast during spring migration through Texas and Oklahoma? Or is there yet another possibility ― was this a larger than normal mid-June northward shift? Another interesting thing about the above eBird maps is that the core area reports don't seem to vary all that much, and then is that explained by sparse eBirder coverage? Or, perhaps, it's a short-term trend of reproductive success and nest site fidelity.

Whatever the case may be, drought conditions are likely an important factor as to why there are so many Dickcissels in Wisconsin right now. Nevertheless, I still think there remains an element of mystery to the quirky migratory movements of Dickcissels.

And now, here are some early July wildflowers:


Prairie Clover


Hoary Vervain


Prairie Cinquefoil

And the bird of the wildflower patch:


Common Yellowthroat

His home:


Pheasant Branch Conservancy


Common Milkweed

Here are some of the insects I encountered this morning:


Red Milkweed Beetle Tetraopes tetrophthalmus


Fourlined Plant Bug Poecilocapsus lineatus


Orthoptera nymph


Banded Hairstreak Satyrium calanus


Stink Bug Euschistus servus


Peacock Fly Callopistromyia annulipes 


Chalcosyrphus chalybeus


Punctured Tiger Beetle Cicindela punctulata


Slender Crab Spider Tibellus sp. 

It's a fine start to July. While this month best defines summer to my senses, birds near the Arctic Circle are already becoming restless. The first southbound shorebirds will soon arrive in southern Wisconsin. There's a slight pause in the action, and then songbirds slowly begin to disappear from the conservancy. It may be dispersal and not migration, but as soon as I see (or hear) a Tennessee Warbler I'll know that fall songbird migration is on.

But for now? Enjoy Summer!


A gorgeous summer sky!

Pope Farm Conservancy, Dane, Wisconsin, US
Jul 1, 2017 9:45 AM - 11:45 AM
34 species

Turkey Vulture
Cooper's Hawk
Sandhill Crane
Mourning Dove
Downy Woodpecker
Hairy Woodpecker
Northern Flicker
Eastern Wood-Pewee
Eastern Phoebe
Eastern Kingbird
Blue Jay
American Crow
Horned Lark
Tree Swallow
Barn Swallow
House Wren
Eastern Bluebird
American Robin
Gray Catbird
Brown Thrasher
European Starling
Cedar Waxwing
Common Yellowthroat
Chipping Sparrow
Clay-colored Sparrow
Field Sparrow
Vesper Sparrow
Song Sparrow
Northern Cardinal
Indigo Bunting
Dickcissel
Red-winged Blackbird
Common Grackle
American Goldfinch

All images © 2017 Mike McDowell

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