Fig. 2
From: Abundance of insects and aerial insectivorous birds in relation to pesticide and fertilizer use
a The number of Swifts during surveys with cars in relation to three principal components with lines representing regression lines and SE. Red, blue and green lines represent PC1, PC2 and PC3. b The number of House Martins during surveys with cars in relation to three principal components with lines representing regression lines and SE. Red, blue and green lines represent PC1, PC2 and PC3. c The number of Barn Swallows during surveys with cars in relation to three principal components with lines representing regression lines and SE. Red, blue and green lines represent PC1, PC2 and PC3