How to monitor nests
When to start monitoring your nest box/nest
Birds can begin nesting in a box any time from February onwards, so it is important to start your monitoring as early as possible in the year. Birds may go in and out of the boxes very quickly, so even if you haven't seen any activity, it's always worth taking a careful look. Most Blue Tits and Great Tits will begin nesting in late March or April, but different species will start nesting at different times. If you see birds flying in and out of the box, it's definitely worth having a look inside, particularly if they are carrying nesting material.
How often to check your nest
To get as much information as possible about each breeding attempt it is best to look in the nest/box on several occasions, though no more than is necessary (so as to disturb the birds as little as possible). A few well-planned visits to the nest/box can provide all the information we need.
Early in the season, check your box(es) once a week or so to see if anything is using them, and carry on checking at this frequency right through the year, as the box may be used for a repeat nesting attempt by a pair which attempted a first brood elsewhere. If you notice that birds have started nesting in your box, or you have an open nest in your garden shrub, start looking inside it once every 4-5 days. That way you will be able to find out how many eggs have been laid and how many chicks have been produced without causing too much disturbance. Don't give up monitoring the nest/box when the birds have successfully left, or the nest has failed, because either the same pair or another pair of birds may try to nest again.
Note that there is never any need to record the number of eggs or chicks in the box/nest more than once per day, even if you are monitoring it with a camera.
Code of Conduct when looking in a nest box
Where possible, we ask Nesting Neighbours participants to look inside their nest boxes to note the stage of the nest, but minimising disturbance to the breeding birds is obviously of utmost importance. Looking inside a box will not automatically cause the parents to desert the nest. Scientific studies have shown that, as long as observers are careful and follow the BTO's guidance, making several visits to a nest to record the contents does not increase the probability of it failing. However, it is important that you take care when doing so.
If you have been watching your box from a distance and know that both the parents are away finding food or nesting material, you have an ideal opportunity to visit the nest. This may not always be possible or practical, however. If you don't know whether a bird is in the nest, then it is important to follow the guidelines below:
- Before looking in the box, give the side a light tap so that any adult birds can become aware of your presence and have the opportunity to fly away before you open the lid
- To look inside, lift the lid very slowly. If there is an adult bird still sitting tight on the nest, quickly look to see if there are any eggs or young in view, before gently lowering the lid and leaving as quietly as possible. Do not attempt to move or flush the adult to get a better count
- If there is no adult present in the box, you are free to make your observations, doing so thoroughly but quickly to avoid staying at the nest for longer than is necessary and leaving as quietly as possible. Note the stage of nest building and the number of eggs or chicks where applicable
- Unlike mammals, the majority of birds have a relatively poor sense of smell, so there is no need to worry about leaving your scent around the nest box. However, handling eggs or chicks is illegal without a special licence in most UK countries, so please just look but don’t touch the nest contents
What if I can't or don't want to look in the nest box?
If you are unable to look inside the box/nest, or do not wish to do so, you can still tell a lot about what is going on in the box/nest just by watching it from a distance. You will need to be close enough to see what's going on at the nest, but not too close as this may prevent the birds from visiting their nest. You may even be able to watch from the comfort of your own home with the aid of a pair of binoculars. There are several signs of breeding to look out for:
- Birds flying repeatedly to and from the nest
- Birds carrying nesting material to the nest
- Birds carrying food to the nest
- Chicks calling from the nest
- Young poking their heads out of the box/nest
- Young leaving the box/nest when they are ready to fledge
If you have found a nest that isn't in a box, such as a Robin nest in a plant pot or a Collared Dove nest on a security light, you can monitor it for Nesting Neighbours just as if it was one of your nest boxes.
As with boxes, it is perfectly safe to monitor these nests, provided you strictly follow the guidelines below. Scientific studies have shown that, as long as observers are careful and follow the BTO's guidance, making several visits to a nest to record the contents does not increase the probability of it failing.
You should monitor open nests at the frequency outlined in the section above. However nests that aren't in boxes are often more difficult to get to and must be approached more carefully, so please take the following precautions:
- Accidental damage – Be very careful when moving any vegetation around the nest, so as to avoid dislodging the nest or causing it to tilt and spill its contents. Be aware also of any other nests near the one you are trying to reach
- Desertion – It is important not to startle a sitting bird, so if a female is sitting tight when you try to visit a nest, just go away and check again later. If a bird does happen to leave the nest on your approach, make a note of the nest contents and leave the area straight away; she will quickly return. Chicks and eggs are exposed while a parent is off the nest, so do not visit in inclement weather
- Revealing a nest to predators – Predators can be assisted by tracks and signs left by people and animals. Avoid leaving a trail to the nest by trying not to displace or trample any surrounding vegetation. Never inspect a nest if you think a predator may be watching you
The above guidance is taken from the Code of Conduct that applies to the BTO's other survey of nesting birds, the Nest Record Scheme. Read the full Code of Conduct.
What to do if the nest has been abandoned
Unfortunately, not all nests are successful. Some may be abandoned by the parents or attacked by predators. If you do find what looks like an abandoned nest, you may be tempted to remove the contents in an attempt to clean the box out for other birds. However, under bird protection law, it is actually illegal to clean out nest boxes during the breeding season, from 1st February to 31st August, in case active nests are inadvertently disturbed. If you do want to clean out the box at the end of the season, wait until the autumn when you can be sure that it is no longer being used. Remember to record the details of the nest outcome on Nesting Neighbours.
Making the most of BirdTrack data
We have been working to produce useful summaries for bird reports using data from the millions of annual BirdTrack records.