[BCNnet] Fw: IBET Black Tern Marsh Management (no sightings)

Tue Aug 14 18:28:40 CDT 2007

---------- Forwarded Message ----------
To: "Illinois Birds" <ILbirds at yahoogroups.com>
From: "boglady" <boglady at owc.net>
Date: Mon, 13 Aug 2007 23:25:53 -0500
Subject: IBET Black Tern Marsh Management (no sightings)

Hi IBETters,
I submit this in response to some voices of concern regarding the water levels of Black Tern Marsh at Moraine Hills State Park / McHenry Dam in McHenry County, Illinois. As birders, we are sometimes the most acutely aware of changes in habitats, especially as it affects birds. So I asked some of our IDNR personnel to share their insights on how the wetland is managed. The following is the Resource Management Plan as written by Natural Heritage Biologist Brad Semel several years back. It does a nice job of explaining the management goals of Black Tern Marsh and of managing for threatened & endangered (and other rare) wetland wildlife in general. I hope this alleviates some of the concerns. I also encourage IBETters to not hesitate to ask questions of our IDNR folks. They are doing their best to balance the needs of all park users - especially the wildlife that depends upon the habitats we manage. Your eyes & ears are appreciated.
Thanks,
Stacy Iwanicki wearing two hats:
Natural Resources Coordinator, Volo Bog State Natural Area & Moraine Hills State Park / McHenry Dam
Private Citizen, Wonder Lake, McHenry County

Black Tern Marsh: Resource Management 

Management of Black Tern Marsh requires special attention to providing suitable habitat for a high concentration of threatened and endangered natural resources. Specifically, management protocols will be implemented that promote and protect the long term health and stability of the suite of threatened and endangered avian wetland species that depend on the site for nesting/breeding and as a migrational stopover. Only cultural and recreational activities compatible with the long term protection of the wetland resources will be permitted. 

Site Management Goals

1. To preserve, protect, and perpetuate habitat of wetland flora and fauna dependent upon the Black Tern Marsh Natural Area Inventory (INAI) site.

2. To provide for public use of the Natural Area consistent with the ecology and historic cultural uses of the site.

Management Program

A. Control of Succession

The vegetative structure and composition of wetlands change rapidly depending upon water level, hydroperiod, and periodic biotic disturbances such as fire. Habitat selection by birds is dependent upon the structure and composition of the wetland habitat. A majority of state listed endangered and threatened bird species breeding at Black Tern Marsh prefer to nest in hemi-marsh, a wetland where the ratio of open water to vegetation is roughly 1:1. If the marsh structure shifts too far from this ratio (either too little water and too much vegetation, or too little vegetation and too much water), the diversity of breeding wetland birds is negatively impacted. Each wetland basin within the marsh complex will be evaluated annually to monitor hemi-marsh conditions, with subsequent management responses to encourage hemi-marsh maintenance. 

Based upon 25 years of observational and breeding bird data conducted by biologists with the Division of Natural Heritage, four management scenarios have been identified which would promote critically needed hemi-marsh structure. A long-term monitoring program designed to quantify vegetation patterns and response to water level manipulations will be initiated to ensure that this objective is met. The following guideline will be used as an aide in defining anticipated water level manipulations:

a. If open-water is dominant and hemi-marsh is in decline, but some breeding of threatened or endangered hemi-marsh dependent species such as black terns is occurring, a drawdown should commence as soon as young have fledged. Water levels should be lowered to minimum levels achievable with the existing water control structure. This will expose mud flats and emergent vegetation and allow greater light penetration in shallow water areas, thereby promoting plant growth and vegetative expansion. Water levels should remain at minimum depths throughout the growing season. Carp, especially destructive to emergent and submerged vegetation, can be eliminated through strategic timing and extent of a drawdown.

b. If open water areas dominate and hemi-marsh is not present, and this is reflected in a downward trend in populations for hemi-marsh dependent species, water should be drawn down early in the spring to the lowest levels attainable with the current water control structure. The drawdown should be initiated after ice thaw to prevent adverse impacts to reptiles and amphibians. This will expose mud flats and allow colonization of annuals and promote the growth of perennial emergent vegetation. This scenario is the most desperate approach and should be used when nesting has not occurred during the previous season and will not likely occur the next year without further intervention. This scenario will likely eliminate hemi-marsh bird breeding activity within the wetland unit during the year it is implemented, but will provide emergent vegetation and breeding habitat the following year. This approach may be implemented as a continuation of the moderate drawdown scenario (a) if conditions warrant.

c. If dense stands of vegetation dominate, with little or no hemi-marsh, water levels should be maintained at a high level throughout the year. This will promote muskrat populations and weaken emergent vegetation, opening the wetland up and creating more hemi-marsh. Prescribed fire may be used to reduce emergent vegetation and to control invasive woody species. Drawdowns may be used in conjunction with prescribed burning to maximize control of vegetation. Care should be taken to prevent the freezing and then raising of the water level in the marsh as this can promote erosion and disrupt hibernating reptiles and amphibians. 

d. Lastly, if hemi-marsh conditions exist within a basin and breeding populations of wetland birds are present, water levels should be marginally lowered toward the end of the growing season to stimulate natural seasonal hydroperiods and thus promote plant vigor.

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