Category Archives: Prairie Photography

Hubbard Fellowship Blog – Lobelias and Pollinators

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A guest post by Anne Stine, one of our Hubbard Fellows.  All photos are by Anne.

Derr Sandpit Wetland Restoration - The Nature Conservancy's Platte River Prairies, Nebraska.

Derr Sandpit Wetland Restoration – The Nature Conservancy’s Platte River Prairies, Nebraska.  September 12, 2013

I was scouting for native seeds in our sand pit restoration across from the crew quarters when I noticed a fascinating pollinator-plant interaction. This activity would’ve been best captured on video with a high quality zoom (which I did not have), but I was able to take pictures.  Bumble bees, and only bumble bees, were fighting their way into great blue lobelias along the edge of our restoration.  Meanwhile, their neighboring cardinal flowers were visited by butterflies exclusively.  Why, and how, were these two closely related flowers so specialized with their pollinator partnerships?

First, let’s consider the great blue lobelia (Lobelia siphilitica).  The architecture of this flower insures that only burly bumble bees can gain access to the pollen and nectar.  Some other insects “cheat” and chew holes in the flower to by-pass the petal-gate, but bumble bees are their primary visitors. Watching the bumble bees pry open the flowers was entertaining. First, they climb onto the flower’s extending ‘tongue’. Then, they push aside the two top petal ‘lips’ and dunk themselves head first into the flower.  Their front half is completely inside the blossom. Only their bottoms and back legs stick out.  They clamber up the stalk, climbing from flower to flower until they reach the top, and then they fly off to visit a neighboring plant.  Because great blue lobelia seems to grow in patches, this is an efficient operation for both bee and blossom.  The bees act drunk on nectar, and the flowers are practically guaranteed a thorough pollination.

Ghh

How bumblebees gain entry to lobelia flowers.

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Success!

Success!

Conversely, cardinal flower (Lobelia cardinalis) is traditionally considered to be a ‘hummingbird-specialist’ plant.  We are just outside the range of the ruby throated hummingbird here on the Platte River Prairies.  Instead, butterflies with their long tongues seem to have taken over the majority of the nectaring and pollination duties.  Or perhaps cardinal flowers in this part of Nebraska predominately self-pollinate.  At any rate, bees weren’t the major customers on cardinal flowers.  Cardinal flowers were visited by butterflies.

How strange that these two wetland con-generics, great blue lobelia and cardinal flower, could grow in intermingled patches and still rely on totally distinct pollinator communities.  Nature is weird and wonderful.

This monarch had the choice between blue lobelia and cardinal flower.  She chose cardinal flower. So did all the other butterflies.

This monarch had the choice between blue lobelia and cardinal flower. She chose cardinal flower. So did all the other butterflies.

This monarch had the choice between blue lobelia and cardinal flower. She chose cardinal flower. So did all the other butterflies.

Isn’t it a little late to be nesting?

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As you might remember, my Photo of the Week last week was an image of a fledgling meadowlark I’d found in mid-September.  At the time, I’d talked about how surprised I was to see such a young bird so late in the season.  Well, last Friday, Eliza Perry, one of our Hubbard Fellows, called me to say she’d just found a nest full of tiny birds – did I want to come take a look?  Of course I did.

American goldfinch chicks sit in a nest about three feet off the ground in a tall thistle (Cirsium altissimum) plant. Platte River Prairies, Nebraska.

American goldfinch chicks sit in a nest about three feet off the ground in a tall thistle (Cirsium altissimum) plant. Platte River Prairies, Nebraska.

I’m pretty sure what Eliza found was an American goldfinch nest.  The bills and markings on the birds look right, and we spotted an adult goldfinch nearby.  However, the best supporting evidence was that the nest was located in a thistle plant (a native thistle species, by the way) and had thistle down in the nest cup.  There is a strong tie between American goldfinches and thistles.  Unlike most other bird species which feed their young on insects, goldfinches instead feed them regurgitated seeds – especially those of thistle plants.  In fact, they often delay their nesting until those thistle seeds have ripened.  Here is a link to photographer/naturalist Stan Tekiela’s post on this topic, if you’re interested in learning more about the topic.

These birds are even further behind the meadowlark in their development, and it’s already getting pretty cold overnight, so the nestlings’ chances for survival might seem slim.  Of course, the difference between the meadowlark and the goldfinches is that the goldfinches have adults around to help them.  Both have a challenging fall and winter ahead of them, but nothing others of their species haven’t dealt with countless times before, I guess.

A better view of the nest placement within the tall thistle plant.

A better view of the nest placement within the tall thistle plant.

Thanks to Anne Stine, our other Hubbard Fellow, who graciously helped hold equipment for me as we photographed the nest.  Because of the very bright early afternoon sun, I had Anne hold a diffuser near the nest to reduce the harshness of the sunlight while I held a small flash unit to better illuminate the birds.  We worked quickly and got out of the way so the parents could resume their feeding duties.