Male Cardinals Fed Nestlings More Often. 143 Hours Counted.

A male Northern Cardinal is bright red and a female is dull brown, and an old idea in biology says a conspicuous bird working at a nest could be a cost to the nest. So how often does the bright one actually come? In this video we walk through a 1997 study in the Wilson Bulletin, where researchers counted feeding trips at 23 cardinal nests near Dayton, Ohio, for 143 hours across two seasons. We cover what was counted and what was not, since trips are not the same as amounts of food, what the paper found about male and female feeding rates, why the average hides pair-to-pair differences, and what the authors conclude about the deflection hypothesis. We also keep separating what the study measured from what its authors infer, and the paper's own limits, including that it did not measure paternity, predator attraction, or load size. 🐦 What's covered in this video: Why a bright red male at a nest raises a question The Ohio study: 23 pairs, 143 hours of observation, 1991 and 1992 How feeding trips were counted, and why trips are not food The three hypotheses the authors tested, including the deflection hypothesis The counts: feedings per hour for males and females, per brood and per nestling Why the average hides differences between pairs Nestling age, brood size, and how the feeding rates changed Why the feeding efforts of mates were correlated What the authors concluded about the deflection hypothesis, and what they did not measure Why this video says males, not fathers, and what the study could not cover Sources referenced: Filliater, T. S., and Breitwisch, R. (1997), "Nestling Provisioning by the Extremely Dichromatic Northern Cardinal," Wilson Bulletin, 109(1): 145–153. Chapters: 0:00 – Red Bird, Brown Bird 0:39 – The Question 1:31 – The Ohio Study 2:12 – How They Counted 3:18 – Three Hypotheses 4:04 – The Counts 4:56 – Not Every Pair 5:41 – Age and Brood Size 6:34 – Mates Match 7:04 – The Verdict 8:13 – Males, Not Fathers 8:42 – The Limits 9:31 – Open Questions Tell me in the comments — if a cardinal pair nests near you, have you ever watched which parent comes more often, and roughly where are you? Subscribe to BirdSense for more of what's actually happening in the bird world, every single week.