We conducted a study in Montreal, Canada, across 97 trees within 24 urban experimental plots to examine bird diversity, avian predation attempts on artificial prey, and the effects of bird exclusion on insect herbivory. We also evaluated local tree diversity and urbanization levels through tree density, impervious surfaces, anthropogenic noise, and human population density. Our goal was to understand how insectivorous bird communities change along the urban gradient, explore their cascading effects on predation and herbivory control functions, and evaluate whether urban tree diversity can help mitigate the negative impacts of urbanization on the trophic cascade involving birds, herbivorous insects, and trees.