PIED-BILLED GREBE

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Pied-billed Grebe
Copyright © 2005 Eric Secker

 Conservation Concern: NONE

Population Trend: Increasing
 Credibility: Mod. Poor

The Pied-billed Grebe is an uncommon breeder in the CW Region.  Preferred habitat usually consists of well vegetated marshes and ponds.  Once threatened in Illinois, the Pied-billed Grebe was recently delisted.  Long-term BCN Census trends show an estimated annual increase of about 2% a year.

Trend Level

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1997-2004 Trend
 Point Count Data		 1988-2004 Trend*
 All Observation Types

*Data gathered using a assortment of sampling methods  - for casual inferences only
  Avg. Yearly
Rate of Change:

The vertical axis numbers represent an index of the population change.

Note that the scales may vary between graphs.

 Avg. Yearly
Rate of Change*:		  
  70%   2%  
   
   

 

 

Technical Notes (1997-2004 Trend)

Sample Size (Indiv.): 20

Sample Size (Records): 15

 

AVG. YEARLY RATE OF CHANGE:
(including standard error)
-28 to 167

  GOODNESS OF FIT:
Chi-square: 22.14, df 17, p 0.1792
Likelihood Ratio: 22.69, df 17, p 0.1597
AIC: -11.31
NOTE: (model fits if p values are above 0.05)

Download Table of All Observations

 
 

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Copyright © 2005 Audubon - Chicago Region & Bird Conservation Network

 
 
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