About Me

35380213_10157882115149573_8522425016141217792_oWelcome to my website. I am a biologist and historian based at the Academy of Natural Sciences of Drexel University (ANSP, Philadelphia, Pennsylvania, USA), and the Editor of the Delaware Valley Ornithological Club (DVOC) and its journal Cassinia. I am a fifth-generation American, born in Pennsylvania and descended from German-Slovak immigrants. My ancestors were soldiers, coal miners, mechanics, nurses, and teachers. I am the first ornithologist in my family tree, to my knowledge.


Ornithology. I am fascinated by secretive species that inhabit dense forests and thickets, about which little is known on account of these circumstances. I wonder what they are up to, and how they got that way. After reading all of the literature that I can find, I collect and analyze original data to learn even more. The Nightingale-Thrushes (Aves: Turdidae: Catharus, Hylocichla) are my favorite study system. I have traveled to many spectacular places in pursuit of them, from Newfoundland and Labrador in Canada, to the Darién Gap in Colombia and Panama. My research combines specimen-based and field methods including phylogenetic analysis of DNA sequences, population genetics, morphometric analysis, video cameras and tracking devices.


History of Science. My interest in history and searching for lost artifacts is probably a side effect of compulsively watching Indiana Jones movies as a kid. Many of the scientists whose lives I study were involved in bird research (including Catharus) during the 19th and 18th centuries. In recent years, I exposed widespread fraud in the works of John James Audubon (2020), transcribed and annotated five unpublished letters of Audubon including the original prospectus for The Birds of America (2015), relocated Audubon’s type specimen of Western Meadowlark (Sturnella neglecta), lost for 150+ years (2016), exposed the composite nature of Alexander Wilson’s “Tawny Thrush” Turdus mustelinus (2018a), demonstrated that Audubon’s famous banding experiment was at least partially fabricated (2018b), relocated Thomas Say’s holotype of an extinct cephalopod, Baculites ovatus, lost for 180 years (2019), and exposed Thomas Jefferson’s unpublished ornithology manuscripts (2018c).




PhD Candidate, Drexel University; Department of Biodiversity, Earth & Environmental Science; Dean’s Fellow / McLean Fellow; GPA:  4.0 / 4.0; Advised by Jason D. Weckstein

Graduate Research Associate, The Academy of Natural Sciences of Drexel University

MS, Natural Resources, Delaware State University; Graduated 2014, GPA:  4.0 / 4.0; Advised by Christopher M. Heckscher


dsc_0239BA, Sociology, Pennsylvania State University; Graduated May 2004, GPA:  3.4 / 4.0

No Degree, Music Recording Technology, Lebanon Valley College; Attended September 2000 – May 2001.


Devon Preparatory School, Devon, PA


I have been involved with scientific research projects in 9 countries. I am also an avid birder, and have contributed over 1400 checklists to the eBird database (Cornell University), including more than 600 within the city limits of Philadelphia, Pennsylvania.

Pennsylvania, USA, July 2019.

73024302_10159161713699573_8902021273803030528_oGeneral collecting expedition with Joseph Sweeney (ANSP) to twelve sites in northern Pennsylvania. I collected data-rich specimens of birds and fireflies (Lampyridae) and Joe collected Ceuthophilus crickets. All specimens were deposited in the collections of the Academy of Natural Sciences of Drexel University (ANSP). One study skin from this collection was recently designated as the neotype of Catharus swainsoni (Halley 2019), and several others are being used in current research projects.

RACN, Nicaragua, March-April 2017.


General collecting expedition to two sites in the North Caribbean Coast Autonomous Region (RACN), in collaboration with the Academy of Natural Sciences of Drexel University and the Biodiversity Institute at University of Kansas (KU). The crew included Mark B. Robbins (KU Biodiversity Institute), Johnathan (Jack) P. Hruska (KU), and Therese Catanach (ANSP). We collected the first data-rich specimens from the humid rainforests of Parque Nacional Saslaya, as well as pine savanna and gallery forest sites near Alamikamba.

Pennsylvania, USA, May-June 2016.

MATTCo-creator and compiler of the Philadelphia Breeding Bird Census, a systematic city-wide survey of breeding birds in Philadelphia county, the cradle of American ornithology. With a team of 75 (!) volunteers, we surveyed a linear distance of 262 km in the Philadelphia park system, counting 15,168 individuals of 101 species, and finding 231 nests of 42 species along the way. Breeding evidence was obtained for 71 species (70% of total). (Halley and Croasdale 2018)

Newfoundland and Labrador, Canada, June-July 2015.


Crew Leader of field expedition to collect genetic samples of Gray-cheeked Thrush (Catharus minimus), conduct avian point-count surveys, and vegetation surveys, in poorly-explored areas of the province. Research coordinated by the State University of New York, Memorial University of Newfoundland, and the New York State Museum. In addition to numerous sites around Newfoundland, we accessed many poorly-surveyed areas along the coast of Labrador as far north as Cartwright.

Delaware, USA, January 2011–October 2013.


Conducted the first intensive field-video-genetic study of the mating system of the Veery (Catharus fuscescens), at a long-term study site in the Mid-Atlantic Piedmont region. This study comprised my graduate thesis at Delaware State University (MS, Natural Resources), under the guidance of Dr. Christopher Heckscher, with whom I have now published several papers on Veery behavior. We were the first to document cooperative parental care and flexible polygynandry in the Veery (Halley and Heckscher 2012; 2013; Halley et al. 2016). Some nests were attended by multiple males, and others by males who were simultaneously feeding at multiple nests themselves, and both sexes had multiple sexual partners. We were also the first to demonstrate (with tracking devices) that Veeries undertake an intratropical migration in January–March, across the Amazon basin (Heckscher et al. 2015). That migration event was discovered by C. M. Heckscher, and it has now been shown to also occur in breeding populations in western North America (Hobson and Kardynal 2015).

Sapzurro, Colombia, October 2012.


Christopher Heckscher (Delaware State University) and I spent a week mist-netting and banding migratory and resident birds with Dr. Nicholas Bayly (Asociación SELVA, Bogota, Colombia), at his lowland rainforest field site in the Darién Gap. We captured multiple species of Catharus, including eastern and western races of the Veery (C. fuscescens, see photo), as well as numerous migrants and tropical resident species. It was spectacular to observe large migratory flocks of swallows and other passerines, careening along the forested ridges of the Caribbean coastline, arriving at last in South America after a long southward journey.

Karnataka, India, September 2009–January 2010.

trekkinggroupI conducted a study of rainforest frogs at an organic spice plantation in the Western Ghats, hosted by Drs. Anurag and Sujata Goel (WAPRED Research Foundation). My study resulted in range extensions for two poorly known Raorchestes species (see Halley and Goel 2012), and the first photographic series documenting the extent of their metachrosis (i.e., color-changing ability). I explored the jungle at night to collect frogs, and then kept them in a terrarium for a couple days at a time, while I photographed and observed them.

Nevada, USA, April 2006 – July 2008.

SATH_innest2For three consecutive breeding seasons, I assisted Dr. Aaron Holmes (Oregon State University) in a study of how songbird and small mammal communities in Sheldon National Wildlife Refuge respond to and recover from wildfire. This project spawned an independent study of biparental incubation and allofeeding by Brewer’s Sparrows (see Halley et al. 2015). I conducted point counts, searched for and monitored nests, deployed and operated small mammal trapping arrays, and ran time-lapse video camera systems at nests to collect behavioral data and identify predators.

Guàrico, Venezuela, September – November 2007.


I assisted Dr. Karl Berg (Cornell University) in studies of vocal learning and communication at nests of the Green-rumped Parrotlet (Forpus passerinus). The study was the first to document vocal learning in wild parrots. I netted, banded and bled adults and nestlings, conducted playback experiments, cross-fostered nests, and monitored behavior via digital video. See “How A Parrot Learns Its Name in the Wild” on YouTube. I also explored the llanos ecosystem on a daily basis, catching snakes, chasing capuchin monkeys, and trying to identify and learn something about everything that I encountered.

Hazeva, Israel, September 2005 – December 2005.

amotz_jaffaI assisted Drs. Amotz and Avishag Zahavi (Tel Aviv University) in their studies of Arabian Babblers (Argya squamiceps), and learned firsthand about the Handicap Principle and their model of (costly) signal evolution. Amotz taught me how to watch and anticipate bird behavior, as we tracked numerous babbler groups through the relatively open desert landscape. For many weeks, we discussed our daily observations over meals, while I asked him questions about evolutionary theory. He took me to the Jerusalem Bird Observatory to volunteer for an afternoon, and paid for my enrollment in a banding (ringing) course in the Hula swamp. He was an important mentor to me during my earliest years as a biologist. Amotz passed away in May 2017 (obit).

Bocas Del Toro, Panama, February 2005 – June 2005.


I assisted Dr. Adam Stein (Syracuse University) in study of signal evolution in a hybrid zone where two kinds of collared manakins (Manacus spp.) meet and interbreed. We lived in remote jungle with a small indigenous community (Guaymí), and located leks in the secondary forest along the river’s edge. We mist-netted, banded, measured, and bled adult manakins, and monitored courtship displays via infra-red video and direct observation. This study was later featured on the front cover of Evolution (2006, 60: 1476–1485).


  • 2017–present — Graduate Research Associate, Ornithology Dept.; Academy of Natural Sciences of Drexel University (ANSP: Philadelphia, PA)
  • 2016/17 — Curatorial Assistant, Ornithology Dept., ANSP (Philadelphia, PA)
  • 2010-11 and 2017–18 (two terms) — Resident Caretaker, Wyck Historic House & Garden (Philadelphia, PA; manuscripts, rare artifacts)
  • American Museum of Natural History (New York, NY; ornithology)
  • Smithsonian National Museum of Natural History (Washington DC; ornithology)
  • Smithsonian Institution Archives (Washington DC; manuscripts)
  • Delaware Museum of Natural History (Wilmington, DE; ornithology)
  • American Philosophical Society Library (Philadelphia, PA; manuscripts)
  • Library Company of Philadelphia (Philadelphia, PA; manuscripts)
  • Haverford College Library (Haverford, PA; manuscripts)
  • Wagner Free Institute of Science (Philadelphia, PA; ornithology)
  • Historical Society of Pennsylvania (Philadelphia, PA; manuscripts)


See publications page or my profile on ResearchGate.


  • 2019 — Witmer Stone Award — Delaware Valley Ornithological Club
  • 2018 — Research Excellence Award — College of Arts and Sciences, Drexel University
  • 2017 — William L. McLean III Fellowship — $27,000 — Drexel University, Dept. of Biodiversity, Earth and Environmental Science
  • 2016 — Julian Potter Award — Delaware Valley Ornithological Club
  • 2016 — Teaching Excellence Award (nominee) — Drexel University
  • 2016 — Travel Award — $300 — Drexel University
  • 2015 — Elected “Fellow of the Delaware Valley Ornithological Club”
  • 2015 — Dean’s Fellowship —$10,000— Drexel University, College of Arts and Sciences
  • 2015 — Carbon Footprint Cup — 32nd Annual World Series of Birding, New Jersey Audubon
  • 2012 — Best Oral Presentation — Delaware State University, Graduate Research Symposium
  • 2009 — Carbon Footprint Cup — 26th Annual World Series of Birding, New Jersey Audubon


  • 2020 — Evolution (ENVS 212) — TA Instructor, Drexel University
  • 2020 — Tree of Life (ENVS 202) — TA Instructor, Drexel University
  • 2019 — Evolution (ENVS 212) — TA Instructor, Drexel University
  • 2019 — Field Ornithology Lab (ENVS 553) — TA Instructor, Drexel University
  • 2019 — Tree of Life (ENVS 202) — TA Instructor, Drexel University
  • 2018 — Evolution (ENVS 212) — TA Instructor, Drexel University
  • 2018 — Field Ornithology Lab (ENVS 553) — TA Instructor, Drexel University
  • 2016 — Field Ornithology (ENVS 580) — TA Instructor, Drexel University
  • 2015 — Evolution & Organismal Diversity (BIO 124) — TA Lab Instructor, Drexel University
  • 2015 — Cell Biology & Genetics (BIO 122) — TA Lab Instructor, Drexel University
  • 2015 — Ornithology (ENVS 606) — Guest Lecturer, University of Pennsylvania
  • 2013 — Advanced Wildlife Biology (NTRS 684) — Guest Lecturer, Delaware State University
  • 2012 — Tropical Ecology (AGRI 548) —Guest Lecturer, Delaware State University
  • 2012 — Ornithology (NTRS 312) — Guest Lecturer, Delaware State University


  • Delaware Valley Ornithological Club (life member, joined in 2014)
  • American Birding Association
  • American Ornithological Society (member since 2017)
  • Philadelphia Botanical Club (Programs committee, 2017–present)
  • Wilson Ornithological Society (member since 2011)
  • Delmarva Ornithological Society (member 2011–2013)
  • Phi Mu Alpha Sinfonia (inducted 2001)


  • Board of Editors – Neotropical Naturalist (2019–present)
  • Editor of Cassinia (2016–present), journal of the Delaware Valley Ornithological Club.
  • Assistant Editor of Cassinia Vols. 74–75 (2015)
  • Field Notes Judge (2019) – Young Birder of the Year – American Birding Association (ABA)
  • Reviewer for The Auk: Ornithological Advances, Wilson Journal of Ornithology, Journal of Field OrnithologyOrnitología Neotropical, Northeastern Naturalist, Pennsylvania Game News


  • 2006 — Sensory deprivation — I floated ~5 times in a sensory deprivation tank at the Restricted Environmental Stimuli Technique (R.E.S.T.) Flotation Laboratory, Penn State University, University Park, PA. My longest session was ~45 minutes in duration.
  • 2006 — Genetic factors relating to sexual behavior — I donated a drop of my blood and answered a detailed survey concerning my sexual habits for my brother Andrew C. Halley’s study examining covariance between DRD4 gene expression and sexual preferences, at Pennsylvania State University, University Park, PA.
  • 2013 — Raw oyster panel — I consumed 10 raw oysters in the Food Sciences Laboratory, Department of Human Ecology, Delaware State University, Dover, DE. (They were pretty gross!)
  • 2014 — Effects of tDCS stimulation on piano jazz Improvisation — I completed three sessions in which I improvised on piano, following a jazz lead sheet, while receiving transcranial direct-current stimulation (tDCS), at the Music & Entertainment Technology Lab, Department of Psychology, Drexel University, Philadelphia, PA, Apr–July 2014.


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