July 28, 2011

Photo focus: Taking land out of CRP is good for prairie-chickens?

I just returned from a quick trip to the Nebraska Sandhills to visit the site of our research on vegetation selection by greater prairie-chickens.  The Photo Focus comes from near Rose, NE.

Water catches the early morning sun as corn is irrigated in Nebraska's Sandhills, near Rose, NE.
Landscape view: corn is irrigated with a center pivot in the midst of pastures in Nebraska's Sandhills near Rose, NE.

I've written (here and here) about the need to re-think models of conservation for wildlife on private lands, because of the uncertainty of Farm Bill programs based on ag commodity prices.  Long-term, sustainable conservation will never be possible under Farm Bill conservation programs, in my opinion.  Short-term, regional effects on populations?  Yes.  But, sustainable habitat for local populations?  No.

And, my opinion is supported by dynamics taking place in the Sandhills.  Many readers will recognize the Sandhills is North America's largest, 'contiguous' grassland--mostly because the sandy soil has prevented large-scale row-crop development.  However, in the eastern Sandhills, there are regions where enough loess is mixed in with the sand to make ranchers/farmers consider planting crops.  Several center-pivot irrigation systems were installed 20-40 years ago.  The look like little islands in a sea of grass as you fly over the region. 

During the past couple of decades, beef prices were high and corn prices were low and fuel prices were high--leading many to abandon the idea of planting crops in the Sandhills.  No profit.  Most farmers (they would probably call themselves ranchers) used the CRP program to plant these circles back to grass.

As adept readers might predict, the current high price of corn and low price of beef has led to the opposite trend.  Several center pivots are now operational again, including the one pictured above.  The eastern Sandhills is not immune to habitat fragmentation under the current commodity price structures.

So, how does this affect prairie-chickens? 

As you might expect, the initial removal of grasslands is bad for any grassland bird.  Less habitat.  But, if we go back 10-20 years, to the time where the landscape was a mix of large, native grasslands with restored pivots (through CRP) in the mix, our current research might actually predict that replacing the 'restored', grassy pivots with corn is a good thing for prairie-chickens.  What?

The problem appears to be how the pivots were restored.  Most were seeded with a mix of native grasses, but were not managed after the initial seeding.  Switch grass has taken over these pivot areas.  Normally, switch grass is considered a fairly decent grass for nesting birds--it is thick and a good place in which to hide a nest. 

But, remember, these pivots are little islands in a sea of mixed-grass prairie--less dense because it's a semi-arid region.  The thick habitat appears to be an "ecological trap"--hens respond to it because it looks like great nesting habitat.  So, they nest in it.  But, predators also respond to it.  Mammalian predators probably find these pivot regions easy to search for nests--they are nice, small patches with lots of birds in them.  Research on pheasants in Iowa has shown that small grassland patches have very low survival, regardless of habitat structure. 

And, that is what our research suggests in the Sandhills.  Although we're still in the preliminary stages, these thick grassland patches have very low nest survival. 

So, given the current landscape and past disturbances creating these circular habitats, my assertion is that planting corn in them is actually better for prairie-chickens than leaving them in CRP.  It will force the hens out into the native grasslands and 'help' them avoid the trap of nesting in CRP*.   Of course, managing the existing CRP in the Sandhills properly is the other option (!), but it is not happening under current USDA guidelines.

That's my prediction and opinion.  I'd enjoy hearing yours.

*Before you take this completely out of context, my lab's research shows that CRP habitat is incredibly beneficial for pheasants and prairie-chickens in row-crop areas of eastern Nebraska.  So, the thoughts above relate specifically to what appear to be interesting dynamics in the Nebraska Sandhills.

No comments:

Post a Comment