Using GIS Mapping to Examine Influence of Forest and Box Spacing on Bluebird Nesting Success (page 2)
An adult Eastern Bluebird can be about 16-21 centimeters long and weigh a total of 30 grams. Between the female and male no difference can be seen in the size. In order to tell the gender of the Bluebird you must observe a tint or shade of their colors. A male Eastern Bluebird has a bright blue upper-part of the body, while the female is a blue-gray in the upper-part. A male also has a rusty or reddish orange throat and a white belly, while the female has a subdued reddish orange belly. Though different in color, both female and male have short black beaks that are slightly arched. They also both have black legs and feet. You can also identify an Eastern Bluebird by its vocalization. An Eastern Bluebird song would sound something like turwy, cherwee, cherey-lew.
Nest Box Description
Now that I have explained how to observe and identify a bluebird I will inform you on their specific needs regarding boxes. Eastern bluebirds prefer their boxes to be at least 300 feet apart. Eastern Bluebirds are remarkably territorial and when it comes to breeding season they expect to have around 2-3 acres to themselves. The bottom of the box should be at least 3 feet above the ground: a box mounted 4-5 feet would be an ideal height. When putting up bluebird boxes it would be greatly appreciated by the birds that you face the entering hole away from prevailing winds and in the summer facing away from the blinding sun. Be ready for your visitors around February in the south and March in the north.
Nest Box Location
The Bluebirds not only have needs for their boxes spacing, height, direction, etc. They have needs for the habitat surrounding the box. When putting up your boxes keep these factors in mind. Bluebirds like to nest in rural suburban areas. During breeding season they must hunt for insects from a perch so small trees, shrubs and a fence post are ideal for successful boxes. Vegetation also plays an important role in the habitat of bluebirds. Mowed lawns, meadows, and grazed fields all compete to be a bluebird habitat. Any places away from the habitat of the bluebird's competitors, like house sparrows or wrens would also be a good place to put a bluebird box. And lastly ideal bluebird habitats are open fields and orchards, where there is absolutely no pesticide spraying and pastureland.
Bluebirds are greatly affected by humans. For example, humans hit a total of 57 million birds with their vehicles each year including many bluebird species. Humans also affect them because they use pesticide in their fields. When this poison is exposed to the insects they are then not safe for the birds to eat because of the chemical. When the bluebird then eats the bug (not knowing of the chemical it was exposed to), it will die. Around 67 million birds die each year of exposure to pesticides including many bluebirds.
- Since bluebird habitat is usually open field or orchard, I expect to find more successful boxes near that habitat. Boxes near forest areas will not be as successful because of competition from other species nesting in the forest and because boxes near the forest will have less protection from predators.
- Since my background reading indicates that the territory distance between bluebird boxes is about 300 feet, I expect boxes less than 300 feet apart to be less successful.
In order to accomplish this project I had to follow many steps. The first thing I had to do was gather my materials. (gloves, nails, data book, pencils, GPS, Arc View, Transportation to all boxes) With the materials I could carry out the first step. The first step was to check the bluebird boxes. Checking the boxes was an extended step, which took the whole summer to do. We checked all fifty boxes about once every three to four weeks. We wrote our data down in our data log. The second step was to get the GPS, which plotted the location of all fifty boxes. We then used ArcView software to plot the points on the maps and to measure distances between variables.
How to check a bluebird box:
- Knock on one of the sides of the box while facing away from the enter hole. We do this so if there are any birds in the box they will fly out before you open it.
- Open the box and analyze information. A bluebird nest would be clean and neat nests that are about 2 - 21/2 inches deep. They are made from grass, string and small twigs. House sparrows have messy nests, often made with trash.
- Write down the data you found. Did birds lay eggs, hatch, fledge, etc.
- Check the boxes once every tree to four weeks to give birds some time to build the next, lay eggs, etc.
**Be sure to bring gloves in case a nest needs to be taken out or replaced**