A Quarterly Journal Devoted To Tennessee Birds Published by The Tennessee MARCH 2020 Vol. 91, No. 1 Ornithological Society THE MIGRANT A QUARTERLY JOURNAL OF ORNITHOLOGY PUBLISHED BY THE TENNESSEE ORNITHOLOGICAL SOCIETY The TOS is a non-profit, educational, scientific and conservation organization. EDITORIAL STAFF Editor: Bob Ford, 808 Hatchie, Brownsville, TN 38012 <[email protected]> Associate Editors: Susan McWhirter, 274 Beech Grove Road, McMinnville, TN 37110 <[email protected]> and Martha Waldron, 1014 Murray Hill Lane, Memphis, TN 38120 <[email protected]> State Count Compiler: Ron Hoff, 166 Chahyga Way, Loudon, TN 37774 <[email protected]> Season Editor: Richard L. Knight, 804 North Hills Dr., Johnson City, TN 37604 <[email protected]> Regional Season Editors: Western Coastal Plain: Dick Preston, 261 Sassafras Circle, Munford, TN 38058 <[email protected]> Highland Rim and Basin: Stephen C. Zipperer, 3105 Chapel Hills Drive, Murfreesboro, TN 37129 <[email protected]> Eastern Ridge and Valley: Richard L. Knight, 804 N. Hills Rd., Johnson City, TN 37604 <[email protected]> Eastern Mountain: Richard P. Lewis, 407 V.I. Ranch Rd., Bristol, TN 37620 <[email protected]> OFFICERS FOR 2019 President: Dr. Steve Routledge, 1515 N. Willow Bend Court, Clarksville, TN 37043 <[email protected]> Vice Presidents: East Tenn. - Rack Cross, 300 River Edge Drive, Kingsport, TN 37660 <[email protected]> Middle Tenn. - Danny Shelton, 705 Countrywood Drive, Franklin, TN 37064 <[email protected]> West Tenn. - Martha Waldron, 1040 Murray Hill Lane, Memphis, TN <[email protected]> Treasurer: Pam Lasley, 5886 Wilshire Drive, Nashville, TN 37215 <[email protected]> Secretary: Cyndi Routledge, 1515 N. Willow Bend Court, Clarksville, TN 37043 <[email protected]> Directors-at-Large: East Tenn. - Susan Hubley, 128 John Sevier Circle, Rogersville, TN. 37857 <[email protected]> Middle Tenn. - Daniel Moss, 395 Janet Drive, Pleasant View, TN 37146 <[email protected]> West Tenn. - Allan Trently, 580 East Lafayette Street, Jackson, TN 38301 <[email protected]> Curator and Webmaster: Charles P. Nicholson, P.O. Box 402, Norris, TN 37828 <[email protected]> Assistant Curator: Dr. Stefan Woltmann, Austin Peay State University, 601 College St., Clarksville, TN 30740 <[email protected]> The Tennessee Warbler (TOS Newsletter) Editor: Theresa Graham, P.O. Box 366, Oakland, TN 38060 <[email protected]> The TOS website can be found at: www.tnbirds.org Send subscriptions & address changes to: Tennessee Ornithological Society, 5886 Wilshire Drive, Nashville, TN 37215 Printed by: Russell Printing Options, 1800 Grand Ave., Knoxville, TN 37916 Copyright © 2014 by the Tennessee Ornithological Society — ISSN 0026-3575575 THE MIGRANT Published by the Tennessee Ornithological Society to Record and Encourage the Study of Birds in Tennessee Issued in March, June, September and December VOL. 91 MARCH 2020 NO. 1 The Migrant 91(1): 1-4, 2020 LEAST BITTERN AND PIED-BILLED GREBE NESTING AT BLACK BAYOU REFUGE, LAKE COUNTY, TENNESSEE IN 2011 Scott G. Somershoe Littleton, Colorado In late May and mid-June 2011, I conducted informal surveys of the marshes at Black Bayou Refuge, Lake County, Tennessee for nesting Least Bitterns (Ixobrychus exilis). Least Bitterns had been documented nesting at this site in the early 2000s (Winstead and King 2006), but there is a general lack of information about the status of the species in the state and even less information about nesting. I documented five active Least Bittern nests and six Pied-billed Grebe (Podilymbus podiceps) nests in a small area of the state wildlife refuge. On 25 May 2011, I conducted a survey of the marsh and discovered one Least Bittern nest with one egg by accidentally flushing an adult off the nest. I found no nests on 26 May. On 16 June, I found five nests with eggs (three nests with one egg and two nests with five eggs) all with adults flushing or being present nearby. The nest first found on 25 May with one egg had five eggs when I checked on 16 June (Figure 1). I did not observe any nests with young. I also found at least four nests with no eggs. It is unknown as to whether these empty nests had failed and the active nests were replacement nests, but Least Bitterns are known to replace lost nests (Poole at al. 2009). All nests were located in a small area of approximately 2.3 acres (1 ha) on the west side of the main levee road that runs generally northeast to southwest. I found no Least Bittern nests on the east side of the levee as the water was either too deep to support marsh vegetation or was too wooded and did not support sufficient suitable nesting habitat. I was unable to conduct subsequent visits to follow up throughout the breeding season to assess nesting success due to time constraints. Water level decreased noticeably between the May and June visits, possibly increasing accessibility by ground based predators, e.g., raccoons, thus providing further incentive not to return and disturb nesting birds. 1 2 THE MIGRANT MARCH Figure 1. A Least Bittern nest discovered Figure 2. Pied-billed Grebe nest at Black Bayou Refuge, Lake County, in relatively small numbers across Tennessee. Tennessee; this nest with 6 eggs was Photo by Scott G. Somershoe. documented at Black Bayou Refuge, Lake County, Tennessee. Photo by Scott G. Somershoe. I detected the majority of Least Bitterns by flushing them out of the marsh rather than by hearing vocalizations, which is not surprising considering their generally secretive nature. Bill Pulliam reported 12 Least Bitterns, all detected by vocalizations without observing any individuals, on an afternoon visit to the site on 4 June 2011, which was between my May and June survey dates. The maximum number of adult Least Bitterns I detected on a survey day was eight, thus suggesting I was not detecting all the birds present on site as I had five simultaneously active nests. While systematically looking for Least Bittern nests, I also discovered at least six Pied- billed Grebe nests containing eggs and appearing to be active (Figure 2). One nest had exposed eggs when I found it, but when I returned 15 minutes later with a camera, the eggs 2020 THE MIGRANT 3 were covered by wet vegetation. I did not detect an adult Pied-billed Grebe at this specific nest. The grebes were especially secretive as there were several active nests in the small survey area. In three survey days, I observed only one Pied-billed Grebe, but heard a few presumed grebes calling and splashing as they fled nests upon my approach. Pied-billed Grebe nests were found primarily on the west side of the main levee, but I discovered two active nests on the edge of the marsh on the east side. Although Pied-billed Grebes have been reported in small numbers in June and July across the state, confirmation of nesting is rare and has generally been by observation of recently fledged, flightless young (Nicholson 1997). Pied-billed Grebe nesting may be more common in marshes across the state than previously known due to the very secretive nature of the birds during the nesting period. Although the occupied marsh site was small, approximately 2.3 acre (approximately 1 ha), the density of Least Bittern nests was quite high at 2.0 nests per acre (5 nests per ha). Least Bitterns are not typically colonial nesting species (Figure 3); nests are not in close proximity (Poole et al. 2009), and nest densities are typically <1 nest per acre (Kushlan 1973, Poole et al. 2009). Higher densities of nests have been reported when habitat conditions are apparently optimal for the species. Densities of 1.2-6.1 nests per acre (1-15 nests per ha) have been reported in Iowa (Kent 1951, Palmer 1962, Weller and Spatcher 1965), 1.2 to 4.9 nests per acre (3-12 nests per ha) in South Carolina (Post 1998), and an exception of 171 nests per acre in an extreme situation in Florida (Kushlan 1973). Figure 3. Least Bitterns are secretive marsh birds and were most often detected by flushing or observation deep in vegetation. Photo by Scott Somershoe. 4 THE MIGRANT MARCH The nest density of Pied-billed Grebes was approximately 2 nests per acre (6 nests per 1.3 ha). Muller and Storer (1999) did not report grebe nest densities, but density of pairs were very low in North Dakota wetlands, ranging from 0.01-0.05 pairs per acre (0.01-0.12 pairs per ha). One Common Gallinule (Gallinula galeata) was heard on 25 May, and one was observed at close range on 26 May. Bill Pulliam reported 10 Common Gallinules on 4 June 2011, most were heard only. Although I searched the marshes thoroughly, I did not document a Common Gallinule nest on my surveys. Pulliam’s report indicated Common Gallinules were apparently much more common on site than I detected and possibly had not yet begun nesting or were not breeding on site. Common Gallinules historically nested commonly in several areas around Reelfoot Lake (Nicholson 1997), but have been reported infrequently in recent years. Shallow water marshes are uncommon in Tennessee, and few areas are managed to support this habitat type. This informal survey suggests that even relatively small areas (5 acres/2 ha) can support modest numbers of nesting secretive marsh birds. Call-playback surveys and subsequent nest surveys targeting secretive marsh birds could yield vast new information on the population and nesting status of many species in the state. Larger wetlands complexes across Tennessee may support largely unknown populations of breeding Least Bittern, Pied- billed Grebe, Common Gallinule, and other lesser known marsh nesting species in Tennessee, including Virginia Rail (Rallus limicola) and Sora (Porzana carolina) (Applegate 2006).