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Laura Behning
75 Glass Spring Rd.
Covington, GA 30014

This is probably the hardest part of color genetics to understand. Once you understand this, the rest is easy!

All horses- regardless of what additional color genes they may have- are either RED or BLACK (red is chestnut) at their base color.

Everything else that you see- and consider a different color- is actually the result of additional modifying genes added to the base color of RED or BLACK. They change the appearance, or phenotype, of the horse- but the horse is still RED or BLACK. RED and BLACK are called BASE COLORS.

Black (which is written as "E", "E" meaning the Extension locus, which is the place on the horse's genetic code where base color is determined) is dominant to Red (which is written as "e"); chestnut/red is recessive to black. This means that if a horse has at least one one black gene, it will be black (or a black based color), and it needs TWO red genes (thus no black gene at all) to be red (or any red based color). In other words, black "covers" red.

Our first and most common modifier is Agouti, the "bay gene".  BAY and BROWN are actually a modification of BLACK. In other words, bays and browns are black horses with a dominant modifying gene- called AGOUTI- added.


Agouti in its dominant form (written as "A") acts to restrict the black of the black horse to just the points- in other words, the mane, tail and lower legs. This allows the red that is "uncovered" by agouti to show through on the body of the horse- in varying degrees depending on the type of Agouti present. Chestnuts can carry agouti, but it won't show on them as they have no black hair to restrict to the points. They can, of course, pass it on to their offspring. Black horses cannot have the dominant, "active" form of agouti, because if they did, they'd be bay and not black. For example, a black x chestnut cross might produce a bay foal; this happened because the agouti, or bay gene, actually came from the chestnut parent, and the black base color came from the black parent.

It is theorized that there are three different types of agouti. "A" is the Agouti which causes "regular" bay; "A+" is the "wild type" Agouti, which results in a light bay horse with very little black on the legs, usually just around the fetlocks; and "At" is brown, or what is sometimes called "seal brown", a nearly black horse with reddish areas on the muzzle and flanks. A horse will either have some combination of the three types, one of the three types plus one recessive agouti gene (the "inactive" agouti gene is written as "a"), or two recessive agoutis ("aa").

Conventional theory is that there is an order of dominance amongst the various agoutis, with wild bay (the most restrictive of black) being dominant to bay, and bay being dominant to brown (the least restrictive of black). Two browns, for example, cannot produce a bay. There have been examples of two bays producing a wild bay, however, so some now think that wild bay is a separate modifier. This would also explain the relative rarity of the wild bay phenotype.

There is a lot of crossover in appearance between very dark bays and browns. A test for the brown type Agouti is offered by Pet DNA Services. This is the only lab which offers this test.

There is artwork depicting a medium shade of each color on each page of our Color Gallery. Be aware that the possible shades in each color may vary (lighter or darker) than what you see in the artwork; the photos used will illustrate those variations in shade. Also, keep in mind that the bay base horse will always be on the left, the chestnut based horse in the middle, and the black based horse on the right. This will help you remember what base color is "underneath" the various dilution genes and modifiers shown on this website.

Click on any picture to enlarge

HOLLYBROOK CARTUCCI (Hollybrook Headliner x Hollybrook Georgia Peach), 2010 bay gelding. This lovely gelding is a most interesting color. As a foal he was a very good silver mimic (see our silver page for more info on the silver dilution), but he does not have a silver parent. His coloring is possibly due to a variant of wild bay. Most typically, wild bays have lower, less defined leg points than Cartucci has. Another common cause for lighter hairs in the mane and tail is a sabino variant, but most sabinos will have more white than just a simple star as seen here. As a two year old (right two pictures), Cartucci's mane has darkened to the more usual black. His tail may retain some light hair or it may, eventually, grow out to be entirely black. You can see a similarly colored Morgan on our sabino page, the mare Unraveled, though her tail is more white than the silvery-gray seen here. Since there is no test available for wild bay, and only one type of sabino, and no test for many yet-to-be-identified genes that may be responsible for some of the unique colors we come across,  we can only guess at the cause of some of them. Cartucci is owned by
Judy and Harry Leneau.

STORMSWEPT CRICKET (Antietam On Command x Bowood Elusiv Dream), 1997 bay mare. Yes, that's the same horse in both pictures! Crickets illustrates the range of shade both within the bay spectrum as well as the range of shade possible in different seasons, at various points in the horse's life, or due to the effects of different feeds. Most people would look at the second picture and say conclusively that this was a seal brown horse. Agouti testing by Pet DNA Services, the only lab which offers testing for brown-type Agouti, proved that this mare is a bay. Her test results were A/At- one bay Agouti and one brown Agouti. Since bay is dominant to brown- meaning if both are present, the bay phenotype will prevail- this mare is conclusively a bay. I've always been a fan of the Jockey Club's designation of "dark bay or brown". In the absence of testing, it really does cover all the bases. The second photo also shows Cricket's Birdcatcher spots, which come and go and are sometimes more or less numerous. Photos courtesy of Cricket's owner, Mary Ann Schaefer.

TOPFIELDS SAMANTHA (Topfield's Shamrock x Miller's Debutante), 1971 dark chestnut mare. Samantha is a good example of a dark chestnut that might be mistaken for a dark bay. The cream and red colored hair mixed in on her fetlocks and cannons tells the tale, however. She was a 3/4 sister to another very strikingly colored dark chestnut mare, Topfield's Janet, who can be seen on this page. Photo courtesy of Mary Ann Schaefer.

ROCKING M STARDANCER (Rocking M Vaquero x Rocking M Jolene), 1992 black mare, with her 2007 colt MMR OBSIDIAN (by MMR Desayado). "Sid" is quite brown for a newborn black foal. Most black foals are black or grayish in color. Photo courtesy of Suzanne Edmonds, owner of both horses.

UDM AMERICAN MADE (UDM Gold Mine x Aljak's Miss Whamerica), 2008 bay colt (pictured as a weanling on the left and as a yearling on the right) owned by Upson Downs Morgans. This colt looked very much like a silver bay foal at birth, but he does not have a silver parent so he cannot be silver. The heavy frosting in his mane may be due to the wild bay gene, or it could be sabino or pangare (also called mealy) at work, both of which he exhibits. His leg points have developed a bit more as he has grown. Photos courtesy of Karen Burridge.

FIRE MYSTIC PRAIRIE DOLL (Little Red Diamond Reo x Old Bay Lippitt Trophy), 2007 chestnut mare, pictured as a yearling. Any color of horse can have a dorsal stripe, as seen here, but that does not mean they are duns. Dun is a dominant gene, so duns must have at least one dun parent, which this mare does not have. She also does not have the diluted body color, leg barring or other characteristics of a dun. Photos courtesy of Amy Edmundson.

WMS LAUREL ZARA BETH (Robbi-Sue's Sweet Success X WMS Laurel Lady Hanna), 2008 bay mare and her companion WMS LAUREL MADLINE (Delmaytion Top King X SBM Lady Jane), 2008 chestnut mare, both pictured as weanlings. Zara shows a great deal of what is commonly called "foal frosting" in her tail. This eventually grows out in most cases. Sometimes white in that tail is due to rabicano or a pinto pattern. Often the cause of a white hairs in a tail can be determined by the location of the white- at the tailhead is more typical of rabicano, at the sides of the tail in a foal or young horse is more typical of "foal flaxen", and at the bottom of the tail, especially when found in combination with flashy white markings, can be due to a pinto pattern (in Morgans, most likely splash or sabino). Photo courtesy of Zara and Madline's breeder, Carol Williams.

MTN TOP ENDEAVOR (Mtn Top Whippoorwill Tanek x Tan War Bird) and MTN TOP BLACK GOLD (Gone Gold x Spring Lake Katefly), both 2009 black colts, playing on a nippy spring morning. This photo illustrates some of the variance in shade of black foals. Photo by Laura Behning.

DREAM CATCHER DARK SKYE (The Scandinavian x SA Danielle), 2006 brown mare, pictured on the left at 5 days old and on the right as a weanling. Skye shows how many Morgans have been misregistered as black over the years! Only the barest hint of tan on her muzzle- and a test for Agouti! - showed she is not black. Photos courtesy of Barbara Fink.

BOBCAT'S WONDERFUL TONITE (Denlore's Desert Storm X Courtland Charisma), 2004 dark bay or brown mare (left) with her owner Catherine LaBarre and COURTLAND CHARISMA (UVM Elite X Disco Dolly), 1990 brown mare with Bob Armstrong. Charisma (aka "Tootsie") was thought to be black, but Agouti testing showed her to have one brown Agouti gene. Black horses cannot have Agouti or they will be modified to bay or brown. Many brown horses are mistaken for blacks, and often Agouti testing is the only way to sort them out. Photo by Denlore Photography.

OKAN STORM KING (Meredith Billirubin X Good News Priscilla), 1997 brown stallion owned by Don & Mary Curtis, Okan Morgans. Photo by Tim O'Neal.

AMADEUS MOZART ARA-LI (Jake Mint X Amadeus Nekomia Ash), 1995 black stallion owned by Ara-Li Acres, New Brunswick, Canada. Mozart is hitched to an 1890 New Brunswick carriage built in Port Elgin. The driver and horse owner is Dawn Brown, and the passenger is Lynn Wells, whose grandfather built the carriage. Both women are friends from Collina, NB, just west of Sussex. They are seen in front of the stagecoach house once operated by Hugh McMonagle of Sussex Vale. This business was the half-way stop for travelers going between Saint John and Moncton. Mr. McMonagle was a prominent local businessman, sportsman and politician in the mid-1800s who introduced the Morgan Horse to New Brunswick. Mozart is a full Lippitt Morgan. (Vanessa Packman photo)

MTN TOP WHIPPOORWILL TANEK (Whippoorwill Talisman X Spring Lake Katefly), 2005 black colt owned by Kristal Homoki of Mtn Top Morgans, PA. Black foals can be born any shade from an inky all over black to a more silver gray as here- or even lighter.

TELISHAN REJOICE (Telishan Santiam X LCS Fine Crystal), 1999 dark bay or brown mare with her 2005 black colt CASTLERIDGE ABOVE, by Above Command. "Joy" is so dark that she might be called brown by some; testing for brown Agouti would settle the question. This "gray area" in defining dark bay vs. brown has led some registries (for example, the Jockey Club) to simply list "dark bay/brown" as a color choice on their registration applications. Joy is owned by Melody Faber of Telishan Morgans, GA and "Abe" is owned by Debi Boies, Castleridge Farm, SC.

TASHOTA'S WARRIOR (Serendipity Storm B X Cambridge Velvetrose), 1984 brown stallion owned by Marilyn Esteb, Stone Pine Farm. Photo by Laura Behning.

WINDEN MY WINGS (Shanghai X Essex Aria), 2005 bay colt owned by Jeanine Key. "Wings" shows that not all bay foals have a starkly black mane and tail; his is a mix of gray, black and brown hairs and with his still-light lower legs, he might be mistaken for a chestnut foal. Chestnut foals, however, generally have a self colored mane and tail in some shade of red like the body. Bay foals' legs shed to black at the foal shed; darker bay and brown foals are born with quite a bit of black already on their legs. All foals can have quite a bit of light hair in the tail. This grows out as the foal matures. This can be seen in the second photo of "Wings"; most of his light hair is at the ends of his tail, and it will eventually disappear. Photos by Tami Johnson, Windenhill Morgans.

GAB CREEK TRAVELER (Funquest Erick x Gab Creek Gay Mashanta), 2004 chestnut stallion owned by Bill and Susan Visi. Pictured as a two year old. Photo by Laura Behning.

The late ANDA'S BALLERINA (O-At-Ka Carl Marshal x Princess Pierette) 1969 chestnut mare pictured at age 36. This grand old mare was a lifetime friend and partner for her owner Sue Colby of Macushla Morgans in NH. She competed in Hunt Seat, Western and Carriage Driving, did extensive trail riding, parades and weddings. She also produced three foals: the bay gelding Macushla Squire Dan (by Medomak Cavalier) who still competes, including over fences, with his young rider; the chestnut mare Macushla Cashmere (by Serenity March Time) who was Sue's Combined Driving horse; and the bay mare Macushla Brenna (by Medomak Sea Splendor), also owned by Sue.

SCATTERED OAKS BOLDVENTUR (Venturous Colonel X New Heritage Laura Knight) is a full Lippitt chestnut gelding, foaled in 2000, and owned by Lisa Algarin, Claywood Farm, SC.

CBMF RUBY (GLB Bell Pepper X Cy Don's Libby), 2000 chestnut mare owned by Paula Reny of ME.

MERWIN ALL A BREEZE (Mr. Breezy Cobra X Merwin's Adonna), 1976 black chestnut stallion (deceased). This horse shows the darkest shade of chestnut- so dark it could be mistaken for black. A close examination of the hair around the fetlocks would reveal a few reddish or silver hairs, a clue that this is not a black horse. All chestnut foals are born some shade of red, and it is only after they shed the foal coat that their true shade of chestnut begins to become apparent. Photo courtesy of Sandra Nichols.

All three photos are of the 1998 wild bay gelding BLYTHEWOOD BEAU BRUMMEL (Equinox Beaubrook X Coreen Ashmore), owned by Pat Thrasher and bred by Kathy Newcomb, Blythewood Morgans. Beau is particularly interesting because his washed out points, including the mixed silver-gray mane and tail, make him a very good mimic of a silver dapple bay. His sire is a brown, so cannot be hiding a silver dapple gene; his dam is flaxen chestnut, and while silver dapple does not "show" on chestnuts, she is from the very prolific breeding program of Frances Bryant, based on Jubilee King and Lippitt lines. If silver dapple was "hiding" in the chestnuts from these lines (and many similarly bred horses have been bred by the Quietude Stud, as well), it is likely we'd have seen it by now. Photos courtesy of Kathy Newcomb.

BUSH CREEK TRILLIUM (Mainframe, chestnut X FCF Escapade, bay), 2005 wild bay filly (pictured as a weanling). This filly's sire appears to be carrying at least one wild bay gene. We know this because "Trilly's" dam is a bay, and if she had a wild bay gene, she'd be wild bay instead of "regular" bay (because wild bay is thought to be dominant to all the other agouti genes). Another wild bay by Mainframe can be seen here, the 2005 colt, Warlock's Eminent Domain. Wild bay is fairly unusual in our Morgan gene pool. If you have a wild bay Morgan, we'd love to feature it on this site! Email Laura Behning with your picture(s). Photo courtesy of Doug Sluiter.
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