Mr. Blom co-authored the National Geographic Field Guide to Birds of North America, published by the National Geographic Society, and taught a course on birding at the Johns Hopkins University.
"Birding defined his life, yet he wasn't one of those who attempted to convert every person he met," said his brother Mark Blom of Ellicott City. "The many pleasant memories I have of him was hearing him tell stories of his exploits and skills in birding."
A tall, rawboned man, he was in good physical shape from his time spent in nature. He refused to complain about his illness as he continued to bird, write and teach for several years after receiving a diagnosis of colon cancer.
"Perhaps the larger tribute to my brother was how he handled his disease - several operations," Mark Blom said. "He handled it with amazing grace."
Mr. Blom was esoteric yet simple in his passion for birds.
His favorite bird was a gyrfalcon, a large, fierce and strong bird found in arctic regions. Yet, he enjoyed driving from his Harford County home in Bel Air to the Conowingo Dam on the Susquehanna River to watch seagulls feed.
"The people who manage the dam blow sirens when they open the floodgates to warn fishermen and boaters downriver," said Bill Thompson III, editor of Bird Watcher's Digest in Marietta, Ohio. "And Eirik marveled how the gulls would respond immediately, sometimes by the thousands, because they knew fish would be stunned after coming over the spillways."
Mr. Thompson, who knew Mr. Blom for 20 years, said his friend and colleague was "extremely smart, articulate, a deep thinker. He had an incredible mind for detail."
Mr. Blom, who also co-authored the Atlas of the Breeding Birds of Maryland and the District of Columbia, worked several years as an editor of Birding magazine and was an accomplished poet.
His family said he took pride in having won four times the World Series of Birding, held annually at Cape May, N.J., and sponsored by the New Jersey Audubon Society. In Mr. Blom's competitive division, teams of four birders attempt to identify the most species in a 24-hour period, midnight to midnight.
"He would tell us of his team piling into a car, birders leaning out of the windows with their binoculars, leaping out in some remote location and listening for a familiar call," Mark Blom said. "He told us that more than 80 percent of the identifications were made by sound rather than visually."
Born in Baltimore, Mr. Blom graduated from Dulaney High School in 1966. He attended Washington College in Chestertown, where he studied English.
He left college before graduating and married Bonnie Jean Kerr of Baltimore and took a job as a reporter for The Dominion Post in Morgantown, W.Va.
That marriage ended in divorce. Mr. Blom later married Betsy Reeder of Clarksville. The couple later divorced.
In addition to his books, Mr. Blom did free-lance work for Baltimore magazine and was a frequent contributor to the op-ed page of The Sun.
He was an avid fan of the Orioles and Ravens, more for his enjoyment of watching sports than their names. Mr. Blom enjoyed engaging in trivia contests about the teams, their players and statistics.
A memorial service will be held at 10 a.m. tomorrow at George J. Gonce Funeral Home, 4001 Ritchie Highway in Brooklyn Park.
In addition to his brother, survivors include his parents, Patricia and Lee Blom of Baltimore; a daughter, Jessie Reeder-Blom of Newark, Del.; and three other brothers, Chris Blom of Baltimore, Andy Blom of Clarksville and Steven Blom of Baltimore.
The family suggested contributions to a memorial fund in Mr. Blom's name at Bird Watcher's Digest, P.O. Box 110, Marietta, Ohio 45750.