What is Killing the Jack Pine?

Sphaeropsis shoot blight

Sphaeropsis shoot blight

Last Fall, my friend Trapper Dave contacted me and asked what was killing the Jack Pine (Pinus banksiana) in a Kirtland’s Warbler planting near his cabin in Oscoda County. This planting was the subject of an earlier blog post. Needles on branches and entire trees suddenly turned brown. We checked other plantings and found dead trees several other places in Oscoda, Crawford, and Montmorency counties. Several of these stands were two year old Kirtland’s Warbler plantings and we became concerned about the impact this die-off might have on this endangered bird.

Trapper Dave contacted the DNR and a helpful Forest Health Technician replied that, “We have had several reports from roughly a four county area of this type of mortality. The pictures you sent are consistent with other pictures we have received from this area… I’ll be sure to send you a some more information once we are able to make a diagnosis.”

Later we received a report from the Diagnostic Services at Michigan State University. They identified Sphaeropsis canker (Sphaeropsis sp. or spp) as the cause of the die-off. From the limited sample, submitted by the Forest Technician, they could not identify which species it was or even if more than one species is involved. The genus is poorly understood and probably has many undescribed species.

Sphaeropsis shoot blight

Jack Pine needles showing Sphaeropsis shoot blight

I looked up the fungus in Tree Maintenance (6th edition) by Pirone, Hartman, Sall, and Pirone. They list another newer generic name, Diplodia but use Sphaeropsis. They write that the fungus “overwinters in infected needles, twigs, and cones. In spring, the small fruiting bodies release egg-shaped, light brown spores… The fungus grows down through the needles and into the twigs, where it destroys tissues as far back as the first node.” (page 425).

Sphaeropsis shoot blight

Close-up of needle showing Sphaeropsis shoot blight spores

Several sources state that the spores overwinter in the cones but I could not find spores in the half-dozen cones I checked. The fungus kills the branches quickly. Die-off appeared over a two-week period but the trees must have been infected for most of the summer.

A USDA Northeastern Area Fact Sheet states, “Sphaeropsis shoot blight, formerly called Diplodia shoot blight, is worldwide in distribution and can infect many conifer hosts. Although many pine species are reported hosts, this disease causes severe damage only to trees that are predisposed by unfavorable environmental conditions. …Other predisposing environmental factors include poor site, drought, hail or snow damage, compacted soils, excessive shading, insect activity or other mechanical wounding. In the north-central United States, the most common hosts are Austrian, Scotch, mugo, red and jack pines grown in ornamental and windbreak plantings.”

We need to monitor the extent of the shoot blight damage in the Grayling area. It is a native fungus attacking a native tree that should have defense mechanisms. It was a dry year in the Grayling area so this may have made the trees more susceptible to infection. I am concerned that the USDA lists Jack Pine plantings, which of course is what we do for Kirtland’s Warbler, as being more susceptible to the infection. I did not find the fungus in the half dozen naturally occurring Jack Pine stands that I checked. If you find this fungus please report the location in the comments section of this blog post.
Copyright 2016 by Donald Drife

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Jack Pine Management

Setophaga kirtlandii

Male Kirtland’s Warbler

In the northern half of Michigan’s Lower Peninsula 150000 acres, approximately 235 square miles, of mainly Jack Pine (Pinus banksiana) are managed to provide habitat for the endangered Kirtland’s Warbler (Setophaga kirtlandii). At any given time approximately 38,000 acres are suitable nesting habitat.

After an area is logged, it is furrowed and then planted with 6 inch [15 cm] tall Jack Pine seedlings. Some Oaks (Quercus spp.) and some tall Pines (Pinus spp.) are left to provide perching sites for the warbler’s territorial singing. Jack Pines are not planted in continuous stands but contain grassy openings. Kirtland’s Warblers nest on the ground, normally at the edges of these openings. When the pines are 5-8 feet (2-3m) in height nesting begins. Nesting continues as long as there are branches touching the ground and the branches of adjoining trees. Four to eight years are required for the pines to reach nesting size and they are suitable for nesting for 12-15 years. After another 30 years or so, the forest is cut for pulpwood and the cycle begins again.

Photo by Bob Anderson copyright 2009

Figure 1 Photo by Bob Anderson copyright 2009

Figure no. 1 shows a Kirtland planting at the end of its first year. Furrows are still visible and you can see the tops of seedling Jack Pines. Figure no. 2 shows the same area five years later. Oak #1 has grown but the “pine stand” is mostly unchanged. Kirtland’s Warblers started to nest in the Figure no. 2 stand.

Photo by Dave Bissonette copyright 2014

Figure 2 Photo by Dave Bissonette copyright 2014

Management areas produce habitat for other species. Hill’s Thistle (Cirsium hillii) is a state threatened species. At most two feet [.6m] high it has large, pink, flowers that dot the plantings. Wood Lily (Lilium philadelphicum) and Sweet-Fern (Comptonia peregrina) also inhabit the areas.  Northern Apple Sphinx Moth larva (Sphinx poecila) feed on Sweet-fern.

Cirsium hillii

Hill’s Thistle

Sphinx poecila

L Northern Apple Sphinx Moth larva R Wood Lily

The Kirtland’s management areas are helping the warbler to recover. It is also altering the landscape, providing homes for a large number of other species.
Copyright 2015 by Donald Drife

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Hello to Mr. Olson’s class at Coweta High School, Coweta, Oklahoma.

Review: “The Kirtland’s Warbler”

William Rapai’s book The Kirtland’s Warbler: The Story of a Bird’s Fight against Extinction and the People Who Saved It covers the first 170-years of the Kirtland’s Warbler from the first specimen in 1841 through the 2010 warbler census. The University of Michigan Press is to be commended as it continues its tradition of providing sound scientific writings in a readable format. The known population has fluctuated from approximately 330 birds in 1974 and 1987 to over 3500 by 2010. After the 1987 census Doug Middleton (an amateur ornithologist) remarked to me that there were more Kirtland’s Warblers in museum cabinets that currently alive. Since the book was written the population has increased to over 4000 birds.

As I write this review, I sit in the heart of “Kirtland Country.” I am only 15 miles from where Norman Wood discovered the first Kirtland’s Warbler nest. A small plaque marks the location. Across the road is Doug Middleton’s stone cabin used for many years as a base for his studies of the Kirtland’s and other Crawford County warblers. I’m in the Jack Pine Plains and during the spring I often hear Kirtland’s Warblers singing.

Nathan Leopold was one of the first to study the Kirtland’s life history. Leopold is better known for the Leopold and Loeb murder in 1924. Before committing this crime, Leopold collected and had mounted a Kirtland’s nest, young, and a male and female adult bird. Through Doug Middleton’s intervention, this habitat study was presented to the Cranbrook Institute of Science and was on display for many years. I saw it numerous times as a boy.

Rapai documents several unique attempts to study the bird. Both Josselyn Van Tyne (curator of birds at the University of Michigan Museum of Zoology) and Harold Mayfield (another amateur ornithologist) attempted unsuccessfully to hand rear young birds. Another plan put forward was to trap the warblers and keep them in captivity each winter. This would remove the hazards of migration and the mortality on the wintering grounds but the plan was never implemented.

In 1971, the Kirtland’s Warbler Advisory Committee was formed. They recommended a Cowbird trapping program and a plan for managing Jack Pine habitat. These have been the keys to the bird’s recovery.

The tragic 1980 Mack Lake fire is also mentioned. Started as a “controlled burn” it lost containment, burning 20,000 acres and killing one firefighter. I walked the area of the fire a week after it burned helping to assess the plant life. I also helped to cut cross-sections of downed, dead trees to determine their ages. I visited the area several times over the next few years as the Jack Pine and other vegetation regenerated.

Rapai points out that the Robin is not technically Michigan’s State Bird and chronicles the attempts to name the Kirtland’s Warbler as the state bird. The Robin was designated the “state bird” via a non-binding resolution and retains that status largely because of tradition.

Rapai mentions the past studies of the warbler’s droppings and current studies being done with pieces of warbler toenails, feathers, and blood samples. Isotopes from these samples reveal what types of food the birds eat, even months earlier when they were on their wintering grounds. He outlines future threats to the bird and calls for continued vigilance to protect the bird’s population

This excellent book preserves the story of the bird’s recovery and the people that worked to make it happen.

Reviewed by Donald Drife

Copyright 2013 by Donald Drife

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