Passengers have faced major delays on Tuesday evening after a fatality on the line and a swan on the tracks.
Commuters faced delays of up to 90 minutes at Euston after emergency services had to deal with an incident between the station and Rugby.
London Northwestern Railway later warned customers that there were further delays and cancellations due to an animal on the line.
Network Rail told the Standard that although the trespassing swan was not the main cause of delays it had created extra difficulties.
The swan was moved but disruption remains until the end of the day at Euston following the incidents.
Avanti West Coast and London Northwestern Railway services to locations such as Liverpool, Edinburgh and Birmingham have been affected, with National Rail warning that trains could be cancelled.
Elsewhere travellers from Marylebone stations are also facing waits of up to 90 minutes for some services.
A fault with the signalling system near Marylebone means trains may be delayed by up to an hour-and-a-half or cancelled, National Rail has warned.
