Tuesday, October 16, 2012

How to tell if birds are breeding in your area.

I have studied a lot of birds in Tenterfield over the years, and this post is a collection of my observations of many different species during their breeding season. I hope it will be useful to anyone who reads it.

Different birds breed at different times of the year, as we all know. Most bird species in Tenterfield breed from August to December of each year, basically during the warmer and wetter period of Spring. Being in a drought still, raising chicks is much higher demand work than non-drought seasons. Survival rates of offspring is dramatically reduced by the absense of a lack of food for the young, developing chicks, and as such breeding seasons are altered by weeks, months or even years. To the extreme side of nature some species may opt out of breeding for a few years until the rains returns. There are so many possibilities that could happen that birds must not only guarantee their own survival but the survival of their chicks if they decide to breed at all.

Okay, let's say you want to know which birds are actually sitting on eggs right now. Firstly you must have some knowledge of the birds' behaviour visiting your area (or garden) prior to reading this information. For example, how often they visit your garden, what they eat, where they eat, and who they eat food with. In the early stages of breeding most adult male birds tend to get aggressive toward other males of their same species. They might also attack other species to chase them away from a nesting area they have chosen. Their songs begin to change at this stage as well.

Territorial birds will always be on high alert for invading rival families trying to steal their territory or mates, and an all out war will commence as a result, with both family groups attacking each other. Both males and females, young and old will get involved.

The very first sign in the birdlife's breeding behaviour though is seeing a second bird hanging around the first one, or suddenly seeing many more birds of that same species, or mated pairs rebonding with each other via song. Birds congregate together during the breeding season to form "mates" or "breeding pairs" and to reestablish their territories as breeding pairs. When they come together they will fight, argue and chase each other. It will be noisy and unless you are deaf or constantly wear headphones whilst playing loud music in your ears, you cannot miss this loud vocalization of the birds. After a few weeks the congregation of birds will separate into pairs of birds and will go their own way. You may only see a few pairs of birds hanging around the immediate area after that happens.

To the actual nesting of breeding birds, their behaviour changes from "Eat, rest, socialize" to "Eat, build nest, Eat, and resting less than normal". Their spent energy is higher than normal finding a suitable nesting site, then spending more time building their actual nest. At the same time more food is needed for them to eat. When nest building birds are not relaxed. They are always on alert and have a lot to be worried about - predators mostly. You might see one of the adult birds (or both) disappear for a while (or altogether). Resident birds that suddenly disappear for days on end is a sign of them breeding - as long as it is within their known breeding season.

However, when birds are sitting on eggs, everything changes, again. Birds are at a very high alert stage as they must protect their eggs at all cost. They must do everything to protect their young from predators, even if it means swooping humans. Birds seem to know that humans are carnivors, and as such treat us as predators just like any other predator bird or animal. (Food for thought: Have you ever seen a Masked Plover or Australian Magpie swoop a sheep, cow or horse?) Just having one stolen egg, or one unhatched egg could mean the end of their chances to breed for that season, or year.

Egg sitting consumes a lot of energy. If both parents are sitting on the eggs rosters are taken. It can actually be very deceiving with birds that are egg sitting because you may only ever see one bird hanging around of that species, whereas in fact there are really 2 birds. Unless you can identify the male from the female with a particular species, you may not be aware that both adults are sitting on the nest. This is also the time when birds go quiet. Birds do not want to be found by predators, when they are egg sitting. Predator birds that eat the eggs of other birds, like the Torresian Crow, will begin to hang around more often, in a chance to steal eggs from nesting birds. But egg stealers seem to target nests in the preliminary stages of just after an egg has been laid, as the egg is fresher and the yolk is still intact. Eggs are stolen and eaten for their high protein content. Egg sitting birds need to eat more at this stage. They need their energy to lay on the eggs and have the strength to counter-attack a predator's attack. Both birds, usually, depending upon the species, experience increases in hormone levels throughout the entire breeding season, and react to threats to their eggs and young under the influence of high hormonal levels. When a bird is sitting on eggs, it will try as lay as horizontally flat as possible and will keep perfectly still if a predator is nearby.

After the eggs have hatched, things change again with the birds behaviour. With the constant demand for food to feed their young as their top priority some species will turn to human handouts for additional food to help feed their young and themselves. It is normal for some species that demand food from humans to beg for food from us at this time of the year. Finding food to feed growing chicks is no easy task. Australian Magpies, for example, feed their young five times a day. With handouts from humans, that's 5-6 trips to the nest by 5 times per day. That equals to about 25-30 mouthfuls of food for just 2 chicks per day, on average. That does not include the food they need to eat themselves, which is more than what they would normally eat when they are not breeding. The parent Australian Magpies also need to feed themselves, and as a result (from the human perspective) looks like the Magpies are starving hungry all the time. If they begin to eat the food themselves, sort of nibble on it, then fly away with some of it in their mouth, you know for certain they are feeding their young. Other species will be seen feeding more times than normal, in a non-stop feeding cycle for most of the day.

However, this is usually the time of year when the big predator birds and reptiles are also breeding, as they depend upon the life cycle of a good supply of juvenile birds to feed their own young with. As sickening as that is to us humans this is just the reality of nature for birds.



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