Saturday, November 12, 2011

insectivorous birds nesting cavities can be encouraged to take wine, and nest boxes. The new research documents that correspond to these birds provide important ecological services pest control producer Weintraub

adult male Western Bluebird Mexican Sialia , photographed in the Bald Hill Park, Corvallis, Oregon (USA). image: Walter Siegmund (Creative Commons Attribution-Share Alike 3.0).

I was in college when I ' After I read the classic book by Rachel Carson

Silent Spring

[Amazon UK, Amazon U.S.]. In his book, Dr. Carson presented evidence that the abuse of pesticides was rampant killing birds and destroying the environment - and also kill humans. This poignant comment on the abuse of chemical pesticides surprised the audience and launched the environmental movement. People to ask:

Is it possible to produce enough food without constant recourse to pesticides and other poisons high resistance

Ironically, not to apply pesticides to crops, while providing at the same time environment friendly birds can control pest populations. A team of researchers led by Julie Jedlicka, NSF postdoctoral member at the University of California at Berkeley, several experiments designed to test this.

"insectivorous birds are often overlooked as sources of predation by pests, however, it is likely that the provision of pest control in many areas, we have only to look," says Dr. Jedlicka. She studied coffee farms friendly birds in Chiapas, Mexico.

"Much of what we know about biodiversity in agriculture in the tropics," he explains. However, we take what we learned in the tropics and apply to the Agriculture in North America

"I went by my doctor wanted to see if we could create bird-friendly farming systems in the temperate zone," writes Dr. Jedlicka in the e-mail. "Having recently moved to California, the vineyards were a logical choice. I was inspired by the efforts of the basis of some producers who created nest boxes Weintraub songbirds in their vineyards."

realize that there was great potential for the research effort by the systematic monitoring of producers Weintraub, "Dr. Jedlicka extended their methods to study the effects of insectivorous birds in agriculture Weintraub. This study focuses on the tiles to the west.

tiles western

Mexican Sialia

generalist insectivores thrushes are found in open coniferous forests and deciduous riparian, semi open - - and in agricultural areas - throughout the western United States and Mexico.

West tiles

nest in cavities. Previous research in California showed that when given the nests have a higher reproductive success than when based on natural cavities: the birds begin to lay eggs before they have higher rates of predation , the chicks have fewer parasites, and their chicks fledge (DOI: 10.1046/j.1526-100X.2002.00129.x).

But because natural nest cavities are a limited resource, the competition between the tiles and other bird species that possess these cavities can be fierce. In addition, Western tiles can not tolerate the presence of another pair of tiles, if the nest is too close, they must be separated by at least 15-30 meters (50-100 feet). Therefore, keeping these habits Bluebird in mind, it is easy to control the density, providing nest boxes suitable for agricultural areas.

Bluebird nest in a vineyard in California Image

:. Julie Jedlicka (with permission).

After placing nest boxes in the vineyard, the team documented, where the tiles spent most of his time over these boxes. As expected, they found that the tiles are concentrated near the nest early in the season, when the couples to take control of his chosen nest cavity, build nests, lay eggs and incubate. As the season progressed, the tiles were observed at greater distances away from their nest more frequently when adults are often seen young birds bluebird foraging in small groups of three to five people (Figure 1, view more)

But what were the effects they have on the birds of insect populations? To answer this question, the team created sentinel prey studies.

"sentinel prey studies, which monitor the elimination of fixed rates, tethered or frozen prey on the ground are common in the literature of entomology, to compare the relative predation pressure under different conditions "the authors explain in their article.

Dr. Jedlicka larvae covered a range of insect species on pieces of cardboard and placed five meters apart between the rows of vines. All pieces of cardboard were in place before 7:00. Dr. Jedlicka returned about six hours later to pick up the pieces of cardboard and placed larvae marked either present or absent - and probably eaten by predators (Figure 2):

As you can see, insect sentinels near active nests bluebird were 3.5 times more likely to disappear than those at random from the vine (controls), indicating a high level of predation resident the tile (Fig. 2, enlarge). Since a previous study showed that each pair of tiles to add five chicks require 124 grams of "bugs" (arthropods) per day (doi: 10.1890/1051-0761 (2006) 016 [0696: AEOVPO] 2.0.CO; 2 ), this level of efficiency is not surprising. A nest containing six eggs Western bluebird Image

: .. Julie Jedlicka (with permission)

A pair produced at least one and often two broods per year in California, and each clutch averages four to six eggs. Young birds of the first brood generally remain in the nest to help parents in the back of the second brood. So with a little math, we see some tiles Western quickly became a group of 12 hungry birds consume 248 grams of insects - a very large number. These include crop pests, although the birds are probably neutral consume insects and predators of arthropod pests.

In this study, not only nesting sites most protected of any pest infestations, but more importantly, there was no evidence that other species of birds can eat grapes were attracted to the nests. Most birds that are considered "predatory grape" not nest in cavities (or nest).

"I think it is important for the public to know that agricultural systems can provide a habitat for wildlife," said Dr. Jedlicka in the email. "There are many ways to design and structure [agricultural area] as highly productive and beneficial for wildlife."

Provide nesting boxes for bluebirds is a low maintenance, low cost and environmentally friendly way to enjoy the "ecosystem services" provided significant that these birds simply being alive. In addition, these methods are adaptable region.

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