Table 1.

Changes in plastic ingestion reported in the literature for seabirds

A. Incidence of plastic in individual seabirds within a study
Fixed EffectsRandom Effects
TermCoefficient EstimateStandard ErrorZ valuePr(>|z|)Number of groupsModel TermGrouping VariableVariance
Intercept−3.080.61−5.034.87E-0759InterceptReference4.30
Year*1.760.384.584.63E-0657InterceptGenus8.61
Method Lavage0.240.310.760.4557Year*Genus0.92
Method Bolus−0.290.37−0.790.43
Method Necropsy−0.290.25−1.190.24
B. Chance of identifying a species that has ingested plastic
Fixed EffectsRandom Effects
TermCoefficient EstimateStandard ErrorZ valuePr(>|z|)Number of groupsModel TermGrouping VariableVariance
Intercept1.320.572.300.02159InterceptReference0.48
Year*0.800.292.730.006357InterceptGenus2.55
Method Lavage−1.710.86−1.990.04657Year*Genus0.019
Method Bolus−0.931.20−0.780.44
Method Necropsy−1.360.55−2.480.013
  • * Year is centered and rescaled for analysis, (year – 1982.365)/10.43.