Exposure to external repeated or long-term stressors can alter animal behaviour and physiology. At zoos, construction of new buildings and habitats is one potential unavoidable long-term stressor. During the construction of a new exhibit near the giraffe enclosure at Lincoln Park Zoo (Chicago, IL), the Zoo’s two female giraffes, Giraffa camelopardalis rothschildi and Giraffa reticulata, were monitored for changes in behavior and faecal glucocorticoid metabolite (FGM) levels during five phases of construction and enclosure access. The FGM analysis was validated by analysing illness and eventual loss of a companion—when one of the giraffes became ill and was euthanised during the study period. In the four months prior to her death, this giraffe exhibited elevated cortisol and corticosterone metabolites; er companion exhibited elevated FGM in the months following her death. Regarding the effects of construction on faecal cortisol metabolite production and behaviour, both giraffes exhibited higher FCMs during the initial demolition phase, but only one individual exhibited elevated FCMs during the prolonged, active construction that followed. This individual also exhibited decreased inactivity and increased locomotion, as well as an increase in the frequencies of abnormal oral and locomotor stereotypies. Such stereotypies included pacing, licking/gnawing of non-food objects, and tongue play during active construction compared to subsequent time periods. IIn addition to such inter-specific and inter-individual variation, both construction and loss of companion were significant sources of stress for the giraffes. Future construction and other stressful long-term events should be paired with careful behavioural and faecal hormone metabolite monitoring, alongside monitoring for variation between individuals, to better inform management decisions regarding zoo animal care.