Wah’Kon-Tah Prairie Nest Monitoring 2017

This season’s nest searching and monitoring project is winding down!  Since mid-May, we have been out on Wah’Kon-Tah Prairie (St. Clair County) daily looking for grassland obligate species’ nests and tracking their nesting cycle.

Cattle grazing on Wah’Kon-Tah Prairie

Our efforts have been confined to two areas of similar size within Wah’Kon-Tah.  One portion has a presence of cattle that have grazing access throughout most of the area, while the other portion lacks the grazing cattle.  Similar to our pilot year on Taberville Prairie Conservation Area in 2016, our research is aimed at studying the effect of patch-burn grazing on nesting success of grassland species.  This project is in conjunction with other MDC efforts to study the effects of patch-burn grazing on Missouri grassland flora and fauna.

Henslow’s Sparrow nest

So far, we have found over 120 nests this season, including more than 60 target species’ nests! The target species’ nests found consist of Bell’s Vireo, Dickcissel, Field Sparrow, Grasshopper Sparrow, and Henslow’s Sparrow.  Other species’ nests we have found include American Goldfinch, Blue Grosbeak, Brown Thrasher, Common Grackle, Eastern Kingbird, Eastern Towhee, Gray Catbird, Indigo Bunting, Mourning Dove, Northern Cardinal, Northern Mockingbird, Orchard Oriole, Red-winged Blackbird, and Yellow-breasted Chat.  Quite a diverse bunch!

Four Grasshopper Sparrow nestlings

 

Black Rat Snake on Wah’Kon-Tah Prairie

Unfortunately, there are plenty of predatory species on the prairie as well!  Coyotes, raccoons, skunks, snakes, domesticated cats and dogs have all been seen or smelled (in the skunk’s case) in the study area.  All of whom will prey on birds and their nests.  A large portion of the nests monitored have failed due to predation.  Snakes are likely the main culprit because the majority of nests predated do not show signs of disturbance, which would be evident had a mammal attempted to raid the nest.

Brown-headed Cowbirds also contribute to nest failure.  As a brood parasite, Brown-headed Cowbirds do not build their own nest or raise their own young.  They rely on the neighboring species to do that work for them.  Despite the reputation of being a freeloader, they put a lot of effort into finding nests and monitoring them until it’s the perfect time for them to lay an egg.  Characteristically, Cowbird eggs require less incubation time to hatch.  Additionally, cowbird hatchlings are typically larger and grow faster than the host species’.  When the cowbird chick has enough strength and mobility it may knock other eggs out of the nest.  Also, due to the increased size and growth rate they can monopolize the food the parent(s) bring, thus causing the other chicks to starve.  As the cowbird nestling grows, it may also suffocate or crowd-out the other nestlings.

Many of our nests monitored this season suffered from brood parasitism.  The species most commonly parasitized during monitoring was that of the tiny Bell’s Vireo; whose eggs look drastically different in size and color.  A Bell’s Vireo nest is meant to house 3-4 nestlings but it is snug with only one cowbird nestling nearing fledging age!  Some species can recognize foreign eggs and will remove them.  Brown Thrasher and Gray Catbird are two of such species.  Between these two species, we have monitored 29 nests.  None of which ever had a cowbird egg or nestling when we checked the nest.

Brown-headed Cowbird fledgling

Bell’s Vireo nest with cowbird eggs

Field Sparrow nest

By now, in late July, most birds have finished breeding for the year.  Many of the remaining nests we are monitoring have nestlings, but we are still tracking nests that are only at the incubation stage.  There are Dickcissel, Field Sparrow, and Gray Catbird nests that are still at this incubating stage.

American Goldfinch nest

 

American Goldfinches have begun building nests and laying eggs recently which is normal as their breeding season is typically later in the summer than most.

Beginning stages of an American Goldfinch nest

In addition to expecting more goldfinch nests, there is a possibility we may find a Sedge Wren nest.  Sedge Wrens have a breeding strategy unlike any other migratory bird.  When they migrate north for the summer they normally pass through Missouri and end in the northern U.S. and southern Canada. However, after they try one or two broods in their northern extent they may migrate south to the central U.S. and try to breed again in July and August before continuing to the southern U.S. where they will typically winter.  A male Sedge Wren was heard singing recently and since males typically arrive before females to establish a territory, we are hopeful it is a sign that the females will be here soon after!

Bell's Vireo Fledgling

Bell’s Vireo Fledgling

Currently, there are dozens of fledglings and juveniles fluttering around the prairie.  Many of these young birds will have to migrate far distances in the fall, so this time is crucial as they must develop flight and feeding skills proficient enough to prepare them for their trip.  Even though the high mortality rate of these young birds is no laughing matter, it is tough not to giggle when a fluffy ball of feathers flushes from nearby vegetation flapping awkwardly and peeping in exclamation!

Erik Ost, MRBO Grassland Field Technician

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