During which specific period is the diet of the White-crowned Sparrow heavily supplemented with protein-rich invertebrates?

Approximately May through July, coinciding with the nesting cycle

The period of maximum invertebrate consumption by the White-crowned Sparrow is closely tied to the demands of reproduction. The text specifies that the consumption of protein-rich arthropods is most pronounced between May and July. This timeframe directly correlates with the time required for egg laying, incubation, and the crucial rapid growth phase experienced by fledglings. During this intense reproductive period, the nutritional requirement shifts dramatically toward protein to support tissue development in the young birds. Following this peak in July, as the nesting cycle concludes and migration preparation begins, the diet gradually reverts back towards the slower-burning energy sources found in seeds and fruits.