BLACK-CROWNED NIGHT-HERON

Black-crowned Night-Heron
Copyright © 2005 Eric Secker

Conservation Concern: 3 State Endangered

Population Trend: Decreasing
Credibility: Poor

The Black-crowned Night-Heron is an uncommon to rare breeder in the CW Region. This species has declined dramatically during the past century. BCN eBird data indicates a large annual decline; however, the sample size is somewhat low and this marshland species is poorly sampled by the BCN Census. Nonetheless, development and urban sprawl has had a notable negative impact on this species in our area.

Trend Level

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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*:

-14%

-10%

Technical Notes (1997-2004 Trend)

Sample Size (Indiv.): 37

Sample Size (Records): 21

AVG. YEARLY RATE OF CHANGE:
(including standard error)
-58 to 29

GOODNESS OF FIT:
Chi-square: 34.52, df 24, p 0.0759
Likelihood Ratio: 39.28, df 24, p 0.0255
AIC: -8.72
NOTE: (model fits if p values are above 0.05)

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