Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Situational Awareness; Fatigue
Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Landing Without Clearance
Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented
Human Factors; Environment - Non Weather Related; Company Policy
On a visual approach; ATC instructed us to contact Tower at the FAF.  After touching down; I realized that I didn't contact Tower.  I quickly swapped to Tower and received Tower's instructions to taxi to the ramp with him.Threats1.  Long duty day (12+ hours)2.  Time of the day (X:XX a.m.)3.  No other aircraft on frequency; which is unusual.  Usually; you are hearing all the other aircraft swapping frequencies.  However; this was late at night during COVID-19 times with less traffic.4.  Previous Maintenance issues; Flight Attendant issues; return to gate event; and aircraft swap; which delayed flight three hours.  We could have discussed that we needed to be extra vigilant on arrival and approach due to the long duty day; time of day; and previous Maintenance issues. Another possibility is that since no one else was on Approach or Tower frequency; the Tower could have reached out to Approach to contact us.
Air carrier First Officer reported landing without a clearance; citing fatigue and scarcity of other aircraft operating due to COVID-19 reductions as contributing.