A neonicotinoid insecticide reduces fueling and delays migration in songbirds

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Science  13 Sep 2019:
Vol. 365, Issue 6458, pp. 1177-1180
DOI: 10.1126/science.aaw9419
  • Fig. 1 Experimental timeline for each cohort of white-crowned sparrows captured on migration stopover.

    The same body measurements were taken ~24 hours apart to compare “pre-dosing” and “post-dosing” conditions. Nocturnal orientation trials tested for baseline migratory activity and orientation, and only birds with fat filling ≥½ the furcular hollow and exhibiting migratory restlessness were screened into the dosing study. Birds were orally dosed the following morning, measured and nanotagged ~6 hours after dosing, and then released 2 hours before sunset. Post-release tracking was accomplished remotely by means of the Motus Wildlife Tracking System.

  • Fig. 2 Effects of a single oral dose of imidacloprid on body condition and food consumption in migrating white-crowned sparrows.

    (A to C) Percent change between pre-dosing and 6 hours post-dosing for (A) body mass, (B) fat, and (C) lean mass in white-crown sparrows measured by using QMR. (D) Food consumption (gram food⋅kilogram body mass−1⋅hour−1) measured over the 6-hour post-dosing period. Control = vehicle sunflower oil; low = 1.2 mg⋅kg body mass−1; high = 3.9 mg⋅kg body mass−1. Boxes indicate interquartile range, middle lines indicate median, diamonds indicate the mean, whiskers show the minimum and maximum values within 1.5× the interquartile range, and dots represent outliers (>1.5× interquartile range from box). n = 12 birds per dose group; food consumption is based on averages per cage (one to three birds per cage) within the same treatment.

  • Fig. 3 Effect of a single oral imidacloprid exposure on stopover duration in migrating white-crowned sparrows.

    Lines indicate predicted probability of departure from the stopover site for each dose group over time. Solid green, control; dashed blue, low dose; dotted brown, high dose; n = 12 birds in control group, 10 birds in low-dose group, and 11 birds in high-dose group. Estimates are adjusted for weather conditions, time in captivity, and predosing fat loads. Shaded area represents 95% CIs, which overlap for the control and low-dose treatments. The probability of departure for high-dose (3.9 mg⋅kg body mass−1) birds was 8.5 times lower than that of controls (sunflower oil vehicle).

  • Fig. 4 Migratory flight paths and overall bearings for 30 out of 33 detected white-crowned sparrows tracked in an automated telemetry array in the southern Ontario, Canada.

    (A to C) Flight paths of (A) control birds, (B) low-imidacloprid-dose birds (1.2 mg⋅kg body mass−1), and (C) high-imidacloprid-dose birds (3.9 mg⋅kg body mass−1). The red circle indicates capture and release site near Long Point, Ontario, and yellow circles indicate tag detections. Lines are drawn between sites with consecutive detections and do not represent actual flight paths, and “×” indicates locations of active radio telemetry receivers during the lifespan of the nanotags. (D) Overall bearing of detection paths. Solid green, control; dashed blue, low dose; dotted brown, high dose. Open circles represent the bearing of individual birds, and arrows represent mean orientation of each treatment group; the length of the arrows indicates how closely individuals are clustered around the mean, the dotted red line indicates the critical values for Rayleigh’s uniformity test at α = 0.05 (vectors that pass this critical value are significant), and the outer arc represents the 95% CI for each significant vector.

Supplementary Materials

  • A neonicotinoid insecticide reduces fueling and delays migration in songbirds

    Margaret L. Eng, Bridget J. M. Stutchbury, Christy A. Morrissey

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

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    • Supplementary Text
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