Department of Biology

Education

2003 - Ph.D. in Environmental and Evolutionary Biology.  Department of Biology, University of Louisiana at Lafayette.

1998 - M.S. in Range and Wildlife Management.  School of Agricultural and Natural Resource Sciences, Sul Ross State University, Alpine, Texas.

1992 - B.A. in Soviet and East European Studies. Department of Slavic and Eurasian Studies, University of Texas at Austin.

Have you seen this bird?

Please be on the lookout for "color-banded" Reddish Egrets along the Gulf of Mexico coastline. In 2006, we initiated a color-banding program for Reddish Egrets nestlings along the Texas coast. From 2006 – 2007, we banded nestlings with orange vinyl tags that attached to the USGS aluminum band on the leg of the bird. The orange tags have an alphanumeric code stenciled on the tag (e.g. A27). In 2008, we begin banding nestlings with colored plastic bands with alphanumeric codes. If you observe one of these "tagged" individuals, please record the location, date, and alphanumeric code (if possible) and any additional information you deem important. See attached form. If you see any of these birds, please report the sighting(s) to Dr. Clay Green, Texas State University-San Marcos (e-mail: claygreen@txstate.edu; phone: 512-245-8037)

 

Research Interests

            My research interests are focused on the ecology and evolution of birds and mammals. Areas of specific interest include the evolution of plumage coloration in birds, especially in plumage dimorphic species such as Reddish Egrets (Egretta rufescens). I am also interested in the evolutionary and ecological significance of sociality in birds and mammals and the effects of sociality in foraging, territoriality and reproductive behavior. Furthermore, I am interested in the conservation implications associated with understanding the social behavior of birds and mammals. I also have graduate students studying a broad array of topics in mammalian and avian ecology including habitat use, reproductive ecology, foraging behavior, and survey methodology. Below are some specific aspects of my research program include:

 

 Influence and ecological significance of plumage coloration in waterbirds

            My doctoral research on plumage coloration in herons investigated the ecological significance of plumage coloration in relation to sociality and foraging behavior. White plumage has apparently evolved independently on numerous occasions in the order Ciconiiforms (herons, ibises and their allies). Closely related species of herons differ considerably in plumage coloration with one species being dark plumage (e.g. little blue heron Egretta caerulea) and one species being all-white (e.g. snowy egret E. thula). I tested several hypotheses related to the influence of white plumage including crypsis to prey, foraging tactics and flock formation and utilization. White plumage has long been hypothesized to facilitate social foraging in herons by attracting birds to a given area. The apparent costs of attracting potential competitors to a given area may be offset by minimizing the risk of predation and/or increase foraging efficiency. Through a series of experimental manipulations with heron decoys, I found white plumage did not serve as a universal attractant to herons and instead species were attracted to like-plumaged and like-size decoys (Green and Leberg 2005). I also investigated inter-individual spacing of foraging white and dark-plumaged wading birds; hypothesizing that if white plumage increases sociality in wading birds, we would expect to find white birds closer in spacing to one another and conversely, dark-plumaged species would be more solitary. In a series of paired observations, we found that white-plumaged species were not closer together than that based on random chance and for snowy egrets specifically, they were significantly further apart than that based on random chance (Green and Leberg 2006). White plumage may confer a foraging advantage in open (unvegetated) water habitat as fish appear to detect the presence of dark plumaged birds (Green and Leberg 2005). However, there was no evidence for this presumed advantage in behavioral comparisons between white and dark plumaged species of herons. Within the plumage dimorphic reddish egret (Egretta rufescens), this presumed advantage was evident in behavioral comparisons between white and dark morphs using specific foraging tactics (Green 2005).   In continuation of my research on the plumage dimorphic Reddish Egret, I have several students examining aspects of this species ecology including potential genetic differentiation, nesting behavior, dispersal behavior and juvenile survival between color morphs.

 

 

Survey and monitoring of waterbird colonies

            While my dissertation research focused on heron sociality in relation to foraging, my postdoctoral research enabled me to study some of the breeding aspects of colonial wading birds and seabirds. Specifically, this research investigated some of the biases associated with surveying waterbird colonies including visibility biases (e.g. white plumaged versus dark plumaged birds) and population estimates. We conducted surveys using two aerial methods, helicopter and fixed-wing aircraft, and compared those colony estimates between one another as well as with ground counts of colonies (Green et al. 2008). We compared two survey methods used in searching a given area for new waterbird colonies: adaptive cluster sampling and line transect with distance sampling(Green et al. 2010). Using past and present colony survey data, we are also investigating the application of Indicator Value Analysis (IVA) to colony surveys in an attempt to identify certain species that tend to nest together. The use of IVA may be an important tool in estimation of difficult to detect species such as dark-plumaged species. After the devastating destruction of Hurricanes Katrina and Rita to the Louisiana coast, we conducted another series of ground counts and examined the effects of hurricanes and drought conditions on colonial wading birds (Leberg et al 2007).

 

 

 Ecology and status of the Reddish Egret

           The Reddish Egret is a globally restricted species with the total population estimated at 5-7,000 adults (Green 2006). However, these numbers are circumspect and recent decreasing trends in historically important areas like Texas suggest these estimates are possibly inflated. Additionally, little or no information exists about the status of Reddish Egrets in the Caribbean Sea as well as Central and South America, most notably Mexico which historically contained significant numbers of breeding adults. Declining population trends of the Reddish Egret are presumably due to various threats including habitat loss (e.g. altered hydrology, development) and colony disturbance (e.g. human-related, introduced predators). Through collaboration with many other agencies including US Fish and Wildlife Service, Pronatura, Coastal Bend Bays and Estuaries Program, a systematic survey of Reddish Egrets throughout most its range was initiated in 2006 and continues today. To date, we have conducted surveys in Texas, Florida Keys, Great Inagua (Bahamas), Tamaulipas (Mexico), Baja California (Mexico)and future surveys are planned for Yucatan, other islands in the Bahamas and potentially Belize and Cuba. Our ultimate goal is to estimate the global breeding population as well as identify important breeding areas within its geographic range. These surveys are necessary to provide the baseline data for long-term monitoring of Reddish Egret populations and estimation of population trends for the species. Identification of important breeding areas within its range will also afford prioritization of research objectives towards examination of specific threats, whether real or perceived, that may be contributing to the overall decline of Reddish Egrets. Our 2-year surveys (2007-2009) on Great Inagua, Bahamas has revealed that the local resident population has experienced a ~50% decline in breeding pairs since the 1980s (Green et al. 2011). In Florida Keys, Reddish Egrets appear to have suffered a considerable decline in breeding pairs; fewer active nests found during surveys in 2007-2008 may indicate differences in available foraging habitat (Hill and Green 2011) as well as threats from disturbance, exotics and habitat loss.

           My lab is also investigating various aspects of Reddish Egret reproductive and behavioral ecology. We are examining potential reproductive differences between color morphs and between regions (Bahamas and Texas). We are also investigating juvenile survival and dispersal behavior using color-banding and satellite telemetry. Our lab is also collaborating with Dr Bart Ballard (Texas A&M University – Kingsville) on an investigation of movement and survival of adult Reddish Egrets using satellite telemetry. Our 5+ years of survey work throughout the range of the Reddish Egrets has yielded considerable genetic samples from nestlings (to date from Texas, Florida, Bahamas, Tamaulipas, Baja California, and Chiapas) and we are finalizing our genetic differentiation analyses between geographic regions and between color morphs.

 

Reproductive Ecology of Waterbirds, both colonial and solitary nesting species

            My lab continues to study varying aspects of the reproductive ecology of colonial and solitary nesting waterbirds. Colonial waterbirds (wading birds, shorebirds, seabirds) are one vertebrate guild that serve as an excellent model for the study of the ecology and evolution of sociality. The evolution of coloniality in waterbirds has been long studied but remains unresolved. The popular information center hypothesis has been refuted by some studies and yet supported by others. Additionally, recent studies suggest colonies may be a product of commodity selection where individuals choose the most suitable habitat (commodity) and as a result aggregate in certain areas. Studies are underway or currently planned for examining 1) the relationship between waterbird colonies and habitat selection, 2) identifying the factors (e.g. prey availability, disturbance, species interactions) that make a particular area suitable habitat while adjacent areas less desirable, and 3) social interactions within a colony . Additionally, extra-pair copulations and/or fertilizations are other examples of commodities individuals may select for in a breeding site and may be more prevalent than originally thought in waterbird colonies. My lab is also investigating factors associated with reproductive success in solitary, territorial nesting waterbirds such as American Oystercatchers.

 

Previous and Current Research in the Green Lab

Previous work

1)     Behavioral and genetic assessment of assortative mating between color morphs of the Reddish Egret (Austin Hill, graduated Dec 2009 and Zachary Holderby, graduated May 2009).  

2)     Examining the affects of human recreational disturbance on foraging and nesting waterbirds (graduate student: Bobby Polak, graduated May 2008). 

3)     Dispersal of Black-capped Vireos in a fragmented landscape (graduate student: Billy Simper, graduated Dec 2010).  

4)     Estimating occupancy and abundance of avian species at Camp Swift, Texas (graduate student: Amber Jonker, graduated Dec 2010).

5)     Evaluation of the species status and development of habitat suitability model for the Gulf Coast Kangaroo Rat Dipodomys compactus (graduate student: Sean Rissel, graduated May 2011).

Current work

1)     Insights into Newell’s Shearwater and Hawaiian Petrel Critical Breeding Habitat Requirements from Remote Sensing and Microhabitat Investigation (Ph.D. graduate student: Jeff Troy).  

2)     The Use of Corridors by Meso-Predators on the Upper Texas Gulf Coast (graduate student: Bryan Carethers)

3)     Inventory of bat species and their habitat use in the Trans Pecos (graduate student: Stephanie Morgan)

4)     Foraging ecology and forage availability for the Black-capped Vireo (graduate student: David Morgan)

5)     Insights into dispersal and site fidelity of juvenile Reddish Egrets using satellite telemetry (graduate student: Brock Geary)

6)     Breeding ecology of American Oystercatchers in Texas (graduate student: Sasha Munters)

   

Courses Taught

Avian Ecology and Evolution (BIO 7102) - Syllabus

Waterbird Ecology and Management (BIO 7328) - Syllabus

Mammalogy (BIO 4422/5422) - Syllabus

Conservation Biology (BIO 7346) - Syllabus

GIS in Wildlife Ecology (BIO 7360) - Syllabus

Publications

Hill, A., and M. C. Green. 2011. The relationship of foraging habitat availability and nest site selection for the Reddish Egret (Egretta rufescens) in the Lower Florida Keys. Journal of Heron Biology and Conservation 1:6. [online] URL: www.HeronConservation.org/vol1/art6.

Oomen, R.A., M.W. Reudink, J.J. Nocera, C.M. Somers, M.C. Green and C.J. Kyle. In Press. Mitochondrial evidence for panmixia despite perceived barriers to gene flow in a widely distributed waterbird. Journal of Heredity.

Green, M.C., A. Hill, Z. Holderby, J. Troy, and B. Geary. 2011. Status of breeding Reddish Egrets on Great Inagua, Bahamas with comments on breeding territoriality and the effects of hurricanes. Waterbirds 34: 213-217.

Reudink, M. W.,C. J. Kyle, J. J. Nocera, R. A. Oomen, M. C. Green and C. M. Somers. 2011. Panmixia on a continental scale in a widely-distributed waterbird. Biological Journal of the Linnean Society 102: 583-592.

Hill, A., and M. C. Green. 2011. Characterization of 12 polymorphic microsatellites for the Reddish Egret, Egretta rufescens. Conservation Genetic Resources 3: 13-15.

Green, M.C., M.C. Luent, and P.L. Leberg. 2010. Evaluation of aerial sampling methods for the detection of waterbird colonies. Journal of Field Ornithology 81: 411-419.

Holderby, Z.P., M.C. Green, and T.R. Simpson. 2009. The effects of body size and roost site on winter die-off of Cave Swallows. Bulletin of Texas Ornithological Society 42: 82-86.

Green, M.C., M.C. Luent, T.C. Michot, C.W. Jeske, and P.L. Leberg. 2008.   Comparison and assessment of aerial and ground estimates of waterbird colonies. Journal of Wildlife Management. 72: 697-706. (pdf)

Bates, E.M., A.M. Fedynich, B.M. Ballard, and M.C. Green. 2008.   Survey of blood parasites from hatch-year Reddish Egrets along the lower Texas coast. Bulletin of Texas Ornithological Society 41: 4-6.

Leberg, P.L., M.C. Green, B.A. Adams, K.M. Purcell, and M.C. Luent. 2007.   Response of waterbird colonies to hurricanes: Loss of individual rookeries has little effect on regional breeding populations.Animal Conservation 10: 502-508. (pdf)

Green, M.C. and P.L. Leberg. 2006. Sociality among foraging Ardeidae: does plumage coloration influence nearest-neighbor spacing? American Midland Naturalist 156: 344-352. (pdf)

Green, M.C.  2005.  Plumage dimorphism in the reddish egret: does plumage coloration influence foraging habitat use and tactics? Waterbirds 28(4): 519-524. (pdf)

Green, M.C., and P.L. Leberg.  2005.  Influence of plumage colouration on prey response: does habitat alter heron crypsis to prey?  Animal Behaviour 70: 1203-1208. (pdf) 

Green, M.C., J.L. Waits, M.L. AveryM.E. Tobin, and P.L. Leberg.  2006.  Microsatellite variation of double-crested cormorant breeding populations in eastern . Journal of Wildlife Management 70(2): 579-583. (pdf)

Green, M.C., and P.L. Leberg.  2005.  Flock formation and the role of plumage colouration in Ardeidae.  Canadian Journal of Zoology 83: 683-693. (pdf)

Leberg, P.L., M.R. Carloss, L.J. Dugas, K.L. Pilgrim, L.S. Mills, M.C. Green, and D. Scognomillo.  2004.  Recent record of a cougar (Louisiana, with notes on diet, based on analysis of fecal materials.  Southeastern Naturalist 3(4): 653-658. (pdf) 

Green, M.C., L.A. Harveson, and L.E. Loomis.  2001.  Habitat selection by collared peccaries in Trans-Pecos, Texas.  The Southwestern Naturalist 46: 246-251. (pdf) 

Guthery, F.S., M.C. Green, R.E. Masters, S.J. DeMaso, H.M. Wilson, and F.B. Steubing. 2001.  Land cover and bobwhite abundance on Oklahoma farms and ranches. Journal of Wildlife Management 65: 838-849. (pdf)

Presentations (Invited)

2010  “Carry on wayward egret: insights into the dispersal, movement, and survival of Reddish Egrets”, Keynote Address at Texas Ornithological Society Spring 2010 meeting, Rockport, Texas.

2010  “Reddish Egrets: Insights into color polymorphism and conservation of North America's rarest heron”, Departmental Seminar, University of Texas at San Antonio, San Antonio, Texas.

2009  “The Reddish Egret: Insights into the ecology and behavior of North America’s rarest heron”, San Antonio Audubon Society, San Antonio, Texas.

2005  Sociality, coloniality, and coloration: implications for the ecology and conservation of wading birds.  Job Seminar, Texas State University, San Marcos, Texas.

2005  Sociality, coloniality, and coloration: implications for the ecology and conservation of wading birds.  Job Seminar, Western Illinois, Macomb, Illinois

2005  Waterbird colony surveys and methodologies, Southwest Refuge Complex Annual Symposium, McNeese State University, Lake Charles, Louisiana.

2005  Reddish Egrets - Louisiana Ornithological Society Winter Meeting, Lafayette, Louisiana.

2004  Reddish Egrets: Mud Flat Dancers.  International Migratory Bird Day Kickoff, National Wetlands Research Center, Lafayette, Louisiana.

2003  The ecological significance of plumage coloration in herons.  Departmental Seminar, Museum of Natural History, Louisiana\ State University, Baton Rouge. 2002   Red, white, and blue herons: Do aquatic prey respond differently to plumage coloration.   Departmental Seminar, Department of Wildlife and Fisheries, Louisiana State University, Baton Rouge.

Presentations

2009  Status of Reddish Egrets on Great Inagua, Bahamas with comments on territoriality in nesting pairs at the Annual Meeting of the Waterbird Society, Cape May, New Jersey.

2008  In over their heads: Sea level rise and coastal storms effects on wading birds at the Annual Meeting of the Waterbird Society, South Padre Island, Texas.

2008  Status update of the Reddish Egret based on rangewide surveys conducted during 2007-2008 at the Annual Meeting of the Waterbird Society, South Padre Island, Texas.

2007  Validation of flight line survey method for Reddish Egrets in Texas at the biannual meeting of the Texas Colonial Waterbird Society meeting in Corpus Christi, Texas.

2007  Validation of flight line survey method for Reddish Egrets in Texas at the 31 st Annual Waterbird Society meeting in Barcelona, Spain.

2006  By land or air: evaluation of wading bird colony censusing using aerial and ground techniques (poster)

2005   Assessment and comparison of aerial and ground count techniques for censusing wading bird colonies at the Annual meeting of The Waterbird Society, Jeckyll Island, Georgia.

2005  Comparison of line transect and adaptive cluster sampling techniques for detecting novel waterbird colonies during aerial surveys at the Joint Annual Meeting of The Waterbird Society and the Pacific Seabird Group, Portland, Oregon.

2002   Foraging ecology of Reddish Egrets in south Texas at the Waterbird Society Annual Meeting, LaCrosse, Wisconsin.

2002   The effect of white plumage and group size on flocking decisions in Ciconiiformes at the American Ornithologists Union, New Orleans, Louisiana.

2001   The effect of white plumage on flocking behavior in Ciconiiformes at the Waterbird Society Annual Meeting, Niagara Falls, Ontario, Canada.

2001   The effect of white plumage and group size on flocking decisions in Ciconiiformes at the American Ornithologists Union, Seattle, Washington.

2000   Microsatellite analysis of double-crested cormorant populations at the Waterbird Society Annual Meeting, Plymouth, Massachusetts.

2000   Landscape composition and structure and bobwhite abundance in Oklahoma at the Wildlife Society Annual Conference, Nashville, Tennessee

2000   Microsatellite and mtDNA variation in double-crested cormorant populations at Society for Conservation Biology Annual Meeting, Missoula, Montana

2000   Preliminary investigations concerning the influence of plumage coloration on wading birds (order Ciconiiformes).  Biology Departmental Seminar, University of Louisiana at Lafayette

 

LINKS

The Waterbird Society

American Ornithological Union

Animal Behavior Society