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Table 4 Multivariable multi-level logistic regression model* estimating the associations between year, clutch number, fledglings in the brood, and hen’s age and the odds of survival among Eastern Loggerhead Shrike fledglings in a captive breeding program in Ontario (2006–2011)

From: Factors influencing mortality in a captive breeding population of Loggerhead Shrike, Eastern subspecies (Lanius ludovicianus ssp.) in Canada

Variable:

OR

95 % CI

P-value

Year of study (1–6):

0.40

0.29-0.56

<0.001

Clutch number:

   

First clutch

ref.

  

2nd clutch

0.34

0.14-0.83

0.018

No. of fledglings in the brood:

1.74

1.20-2.54

0.004

Breeding female age (years):

   

log(female's age)

37.00

3.04-451.01

0.005

(log(female's age))2

0.25

0.09-0.70

0.008

Random effects parameters:

Variance

95 % CI

<0.001

Pair ID

1.40

0.49-4.03

 

Clutch ID

2.23

0.93-5.36

 
  1. *Multilevel model includes random intercepts for clutch (Clutch ID) and breeding pair (Pair ID).
  2. Likelihood ratio test testing the significance of the random intercepts in the model.
  3. ref. = Referent category.