A pine marten year

January	Activity levels are low and martens spend a lot of time resting in dens.
February	Pregnancy starts with implantation of blastocysts; pregnant females select natal dens that offer good shelter, insulation and protection from predators; young born the previous year disperse.
March	More sub-adult dispersal; many litters born in mid- to late March.
April	More litters born; moult starts in adults around the muzzle, with pale fluffy winter coat replaced by short, dark summer coat; adult activity increases.
May	Marten kits’ eyes open and weaning starts, so mothers bring fresh prey to natal dens; kits first appear at den entrances in late May (and sometimes fall out!), so mother martens may move their kits to new den sites where they can learn to climb safely.
June	Marten kits grow in confidence, become more boisterous in their play and follow their mothers on hunting trips away from the natal den; mating activity starts, with adult males visiting mothers at their den sites.
July	By mid-July, the kits appear as big as their mothers and begin to move around her home range independently; the mating season continues, with adult males travelling widely in search of oestrus females.
August	Mating season comes to an end; kits become independent but still tolerated within mother’s home range; martens eat a lot of fruit and insects.
September	Juveniles reach adult size but still stick together within mother's home range.
October	Moult starts, with long, fluffy winter pelage replacing summer coat; activity levels start to reduce.
November	Martens spend less time out foraging and more time in dens resting.
December	Martens spend less time out foraging and more time in dens resting.

Information from the book Pine Martens by Johnny Birks .