Birds are racing against the clock when it comes to building their nests, says Carrie Carey of the RSPB.

A flicker of red downy breast is the only hint of secret activity taking place in the workshop at RSPB Titchwell Marsh. In this unlikely setting, just feet from our busy office, a robin has made its nest in an old shoebox. Robins will nest almost anywhere and have been known to choose the oddest sites including post boxes, hanging baskets and coat pockets. I've even heard of one presumptuous robin who chose to make its home in the folds of an unmade bed!

Most birds are working against the clock when it comes to building a nest for their young. They usually only have a few days to construct their new home and are often hampered by bad weather or disturbance. Requirements vary from species to species but birds seem to instinctively know the exact design needed to build the perfect abode.

Take a stroll through the reserve at Titchwell Marsh and you can see evidence of this remarkable workmanship taking place. Nests vary in shape and size from the messy, unruly constructs of wood pigeons and crows to the neatly-formed cup shaped nests of the finch family. Larger birds can usually afford to be less fussy, as trying to hide in a dainty nest is probably a waste of time. Wood pigeons and similarly-sized birds tend to build high in the tree canopy. They select an appropriate site and drop gathered sticks in the general area. Although this is a haphazard approach, in time enough material will lodge in the tree and an untidy nest is established. You and I might think that one stick looks much like another, but even pigeons can be difficult to please when it comes to finding the right building materials. The process can be quite involved as stick after stick is rejected. These birds might not get a prize for architectural elegance but it is great fun to watch their construction antics.

Smaller birds such as tits, wrens and robins feel more vulnerable and take time to find a place tucked away from common thoroughfares. Many birds will produce two or three broods each year so a thickly-growing shrub provides excellent cover all year. As the vegetation becomes more rampant late nests may be re-established higher in the hedge sometimes camouflaged by moss or mud to blend in to their surroundings. Catching these builders in action can be tricky as they will often stop to check they are not being watched.

Male wrens choose this type of habitat to set up their territory and will make several beautiful domed nests so his mate can have her choice. Generally, although obliging partners, most males will leave the female to do all the hard work and build the nest. Such is the case with one diligent blackbird who has taken up residence on a small ledge beneath the workshop's roof. She began the intricate business of nest building in early March, first layering strands of grass and small twigs to form a base before building up the sides.

Blackbirds build very substantial nests and line them with mud for strength and insulation. Much in the same way as a potter uses his hands to shape a clay bowl, the blackbird uses her chest to create the required shape. With a steady rhythm the bird turns around in the nest while drumming petite feet on the nest floor. It's this turning action that smooths the sides while the gentle pounding compacts the base in preparation for the eggs.

Other birds favour less labour-intensive methods. Not all species have the lofty ambition of making their homes in tree canopies or cliff edges, some are happy to nest on the ground. There's risks with this strategy so site selection can be crucial; species such as harriers select well-concealed spots while ringed plovers and other seabirds depend on the surrounding habitat to provide its own camouflage. Titchwell's harrier population will roost deep in the reedbeds.

It is usually the male that contributes the most to nest building activity. From Fen Hide visitors can get close-up views of these engaging raptors flying low over reedbeds gathering nesting materials. Suddenly they will disappear amongst the reeds as their offering is added to the build. However, it's not without risk, nest sites too close to the water's edge are prone to flooding, those closer to the reedbed boundaries are vulnerable to disturbance. As with many low-lying nests, it's an open invite to predators.

Half a mile away on Titchwell's beach some of our seabirds are beginning to nest. For ringed plovers, the very habitat that conceals the nest can also be its downfall. Little more than a shallow indentation, the nest is superbly camouflaged in the shingle substrate. It's a great trick to avoid predation but sadly, many nests are damaged by beach visitors who don't notice the flimsy structure under foot. As Norfolk's beaches become

more widely used for recreation, nest disturbance is on the increase.

This means that birds are spending less time sitting on eggs and more time rushing away! Parent birds are exhausted, eggs fail to hatch, fledglings are left defenceless - it's not the best scenario for these colourful little waders.

The RSPB is responding nationally and locally to protect breeding habitats for birds and other wildlife. We recognise that visitors may not be aware of the adverse impact that disturbance can cause so at Titchwell we have created 'safe zones' where wildlife can breed undisturbed. We still want people to visit and enjoy our stunning landscapes and experience nature up close but need help in protecting our most vulnerable species. Here are three simple ways you can help:

1 Have fun in our wild places but be aware of potential disturbance around nesting birds

2 Enjoy special encounters with wildlife but keep a safe distance from nest sites

3 Your dogs are welcome along the West Bank path and on the beach but please keep them on a lead near the beach cordon.

By working together and respecting our safe zones, wildlife has a better chance to survive and thrive.