To build a nest is to nidify.
A bird collecting twigs and string is an example of nidify.
intransitive verb-·fied·, -·fy·ing
Origin of nidifyClassical Latin nidificare from nidus, nest + facere, to make, do
intransitive verbnid·i·fied, nid·i·fy·ing, nid·i·fies
Origin of nidifyLatin nīdificāre nīdus nest ; see sed- in Indo-European roots. -ficāre -fy
(third-person singular simple present nidifies, present participle nidifying, simple past and past participle nidified)
- (zoology) To make a nest.
From Latin nÄ«dificÅ (“build a nest"), from nÄ«dus (“nest") + faciÅ (“make, do").