USA: chickadees, nuthatches in conifers increase tree growth


This video from the USA is called Brown Headed Nuthatch 2nd nest [this season].

From the University of Colorado at Boulder, USA:

Chickadee, nutchatch presence in conifers increases tree growth, says CU-Boulder study

Chickadees, nuthatches and warblers foraging their way through forests have been shown to spur the growth of pine trees in the West by as much as one-third, according to a new University of Colorado at Boulder study.

The study showed birds removed various species of beetles, caterpillars, ants and aphids from tree branches, increasing the vigor of the trees, said study author Kailen Mooney. Mooney, who conducted the study as part of his doctoral research in CU-Boulder’s ecology and evolutionary biology department, said it is the first study to demonstrate that birds can affect the growth of conifers.

“In a nutshell, the study shows that the presence of these birds in pine forests increased the growth of the trees by helping to rid them of damaging insects,” said Mooney. “From the standpoint of the trees, it appears that the old adage, ‘the enemy of my enemy is my friend,’ holds true.”

A paper on the subject by Mooney was published in the August issue of Ecology, a monthly science journal. Mooney, who received his doctorate from CU-Boulder in 2004, will become a biology department faculty member at the University of California, Irvine, in fall 2007.

In the study, Mooney used mesh netting to exclude birds from ponderosa pine limbs in the U.S. Forest Service-managed Manitou Springs Experimental Forest northwest of Colorado Springs for three years. The results showed that branches on 42 trees rigged to exclude birds had 18 percent less foliage and 34 percent less wood growth by the end of the study.

Mooney collected about 150,000 insect specimens from the mountain study area, identifying more than 300 separate spider and insect species collectively known as arthropods. The trees used in the study were set up to exclude birds, ants, or both, since ants also can have significant impacts on other arthropods, he said.

“The study indicates that pine canopies are very complex systems with an unexpected level of biodiversity,” said Mooney. “Forest managers really need to look at the big picture of ecosystems and not just focus on trees when implementing regulations aimed at encouraging the growth of healthy forests.”

The study also has implications for large areas of the West ravaged by forest fires in recent years, he said. A number of once formidable stands of mature ponderosa have been burned and logged and subsequently replaced by smaller pines that offer limited breeding opportunities for cavity-nesting birds like chickadees and nuthatches, which nest and lay their eggs in the holes of large trees and dead snags.

“This is a very rigorous study that essentially shows that even modest little birds like chickadees and nuthatches can help improve the heath of the trees, which are the monarchs of the forest,” said CU-Boulder biology Professor Yan Linhart.

North American nuthatch species: here.

Black-capped chickadees and winter: here.

Mountain Chickadee: here.

Birds of Central Park, New York: here.

American chestnut trees: here.

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4 thoughts on “USA: chickadees, nuthatches in conifers increase tree growth

  1. NestWatch Data in Action: Studying Hybridization in Titmice

    Where the ranges of two closely related bird species overlap, individuals of each distinct species sometimes interbreed and produce hybrid offspring that are a mixture of both. Claire Curry (Ph.D. candidate, University of Oklahoma, Norman) is studying this phenomenon in Tufted and Black-crested titmice in Texas and Oklahoma to determine what exactly it is about the biology of these two species that enables them to interbreed and why this interbreeding results in a distinct zone where hybrid titmice occur.

    “The titmouse system is great for studying the process of hybridization because there is an older hybrid zone in Texas, where the two forms have been interbreeding for thousands of years, while in southwestern Oklahoma the Black-crested Titmice have only recently arrived within the past 100 years following the expansion of mesquite trees due to fire suppression and overgrazing,” explains Curry. “I’ll be using NestWatch data to test if the two distinct species and their hybrids differ in their nesting success. This measure of evolutionary fitness is important to help distinguish among several theoretical models of why hybrid zones exist. Data gathered by NestWatchers will be an important piece of the puzzle when I combine it with behavioral data that I have also gathered.”

    Wondering if you have seen a hybrid titmouse? Here’s what to look for. Hybrids in Texas are only found in a narrow strip about 25-30 miles wide that stretches from the Gulf Coast northward through Austin and past the western side of Fort Worth, and then extends to the west at the Red River. In Oklahoma, hybrids are only found in the extreme southwestern corner of the state from just west of the Wichita Mountains northwestward to the Texas panhandle. Crest color of hybrid titmice ranges from gray to jet black. The foreheads of hybrids typically are brown or chestnut, while Tufted Titmice have black foreheads and Black-crested Titmice have pale foreheads. Identification of hybrids is especially difficult at the edges of the hybrid zone because their plumage looks closer to that of the adjacent distinct species.

  2. Pingback: Great tits’ individual personalities | Dear Kitty. Some blog

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