Striker at Portman Road until May with view to a permanent deal
The 25-year-old striker, who trained with Blues this morning, will remain at Portman Road until May.
David started his career at Notts County and made his debut for them as a 16-year-old before joining Southampton.
He went on to make 75 appearances for Saints in a five year spell, then headed to Nottingham Forest in 2009.
He has played more than 74 times for Forest but spent the first half of this season on loan at Coventry, where he rattled in 16 goals in 22 League games to head the League One goalcharts.
The frontman, who becomes a free agent in the summer, has been handed the number 16 shirt.