Masaru Hasegawa

The paper analyzes tail fork depth diversification in hirundines to determine whether it evolved via sexual selection or viability selection, finding a late burst consistent with sexual selection.

The paper tests the juvenile-mimicry hypothesis in swallows and martins, finding a quadratic relationship between juvenile numbers and adult-juvenile resemblance.

This study supports the sight-line hypothesis by showing that eyeline direction in terns correlates with foraging behaviors requiring accurate aiming.

The paper examines if sexual tail dimorphism explains speciation rates in swallows and martins, finding a positive association between dimorphism and speciation.

This study uses isotope analysis of bird eye lenses to reconstruct early-life dietary and environmental history, showing that lens isotopes reflect prenatal and postnatal diet changes.

The paper identifies pseudo-tail spots in barn swallows as a potential early stage of deceptive ornamentation, with low frequency and slow evolutionary change.