This is an appeal from a judgment upon conviction of grand larceny of a bay work mare. Inasmuch as the basic challenge to the conviction questions the sufficiency of the record to sustain the verdict and conviction, a somewhat detailed statement of uncontroverted fact follows. The case involves two similar horses, both unbranded bay mares. Photographs of each of these horses were introduced into evidence, and the horses themselves will be referred to by means of these exhibits. Exhibit 1 is a “straight bay” mare with no white markings, approximately 1400 lbs., and is unbranded. Exhibit 4 is a “blood bay” (more reddish) mare, unbranded, about 1360 lbs., with some white markings of the face and legs.
Appellant and his wife lived on a ranch outside Marsing, Idaho, where they raised and bred horses and other livestock. Appellant also engaged in horse racing throughout the northwest. In May of 1975, while on the racing circuit, appellant purchased a bay mare at auction in Hermiston, Oregon. He had the horse immediately loaded into his trailer and set out for Marsing, some 300 miles distant. He arrived at his home around 2:30 in the morning, and released the mare into the pasture. He woke his wife, told her he brought a new horse back, and requested her to pack a lunch and to wake him after a couple of hours. Upon awakening, appellant left again for the racing circuit.
Appellant’s wife noticed a bay mare, which she later identified as exhibit 1, in their pasture around 8:00 a. m. the following morning. Her husband had left by this time. This mare soon came into heat, and appellant was informed of this fact by tele*465phone. Appellant returned and had the mare bred to his own stud, a recurring practice over the summer. Appellant and his wife concluded in the fall that since the mare hadn’t caught she must be barren and should be sold as opposed to keeping and feeding her over the coming winter. Accordingly, appellant sold the mare, exhibit 1, in late November 1975 to Rayne & Seal, livestock dealers in Nampa.
Approximately a week prior to this sale, appellant’s neighbor, Mitch Quintana, was informed by his ranchhands that some mules and a couple of horses, including a bay work mare, were missing. Quintana called the appellant to see if some of the animals had strayed onto the appellant’s property. Appellant’s wife testified that such straying was a common occurrence over the summer while her husband was away due to the condition of the fence separating the Quintana and Anderson properties. Both appellant and his wife testified that they had on occasion taken animals back to Quintana’s. Upon being called by Quintana, appellant stated that the mules and a mare were at his place; appellant later testified that he was referring to the mare, exhibit 4, at that time. Both appellant and his wife testified that this was the first time they had seen that mare on their property.
Quintana went to the appellant’s ranch to recover his stock. Appellant attempted to return the mare, exhibit 4, to Quintana by driving it in with the mules. Quintana denied ownership of this mare, as did appellant. A discussion concerning another mare apparently took place but it is unclear exactly what was said. Quintana and his hand eventually left with the mules and another stray horse, leaving exhibit 4 at the appellant’s.
Still looking for his missing horse, Quintana called Rayne & Seal, who informed him that they might have his mare. He went to the sale yard and identified the bay mare, exhibit 1, previously sold to Rayne & Seal by appellant as his own. Owyhee County Sheriff Nettleton was then called, and met with Quintana and Rayne at the yard.
The following day, Sheriff Nettleton, along with a state brand inspector, visited the appellant’s ranch. Appellant informed them that he had a horse there that didn’t belong to him, indicating the blood bay mare, exhibit 4. The sheriff and brand inspector then questioned appellant and his wife about the other mare, exhibit 1, sold to Rayne & Seal. Appellant stated that he had sold a bay mare to the dealer, and .upon request, appellant’s wife went into the house to get some documents concerning the horse and the sale. The appellant, his wife, the brand inspector and the sheriff later that day met at the Nampa sale yard where appellant identified the horse, exhibit 1, as the one he sold to Rayne.
Soon following these events, Rayne telephoned appellant and stated that the mare sold had been impounded or returned to Quintana, and that therefore he wanted the earlier payment made for the horse returned or other arrangements made to square the account. Appellant then loaded the blood bay mare, exhibit 4, into a trailer and took it to Rayne, who accepted it as a replacement for exhibit 1. Appellant testified that, though he always thought exhibit 1 was his mare, in light of the circumstances, including being told the straight bay mare was Quintana’s, he took exhibit 4 as a “replacement,” assuming it must have been his mare. In mid-December, 1975, Sheriff Nettleton arrested appellant on the charge of grand larceny for the sale of Quintana’s mare, exhibit 1. See I.C. §§ 18-4601, 4604. After trial, the jury found appellant guilty and the court sentenced him to an indeterminate term not to exceed five years.
Appellant raises a number of issues on appeal, embodied therein being the contention that all necessary elements of the offense of grand larceny were not proven and the evidence thus is insufficient to support the verdict. The court agreeing with appellant on this score, the other arguments need not be addressed.
*466Larceny is a crime of specific intent, and this mental state is an element which must be proved beyond a reasonable doubt by the prosecution. I.C. §§ 18-114, 18-4601. This element was examined at length in the recent case of State v. Erwin, 98 Idaho 736, 572 P.2d 170 (1977). An understanding of today’s decision requires an awareness of the factual setting in that earlier grand larceny prosecution.
In Erwin, this court cast the issue presented as whether the evidence as a matter of law, beyond a reasonable doubt, warranted a jury finding that the defendant was possessed of the specific felonious intent required by law for a conviction on the charge of grand larceny. This court found the evidence there insufficient to prove the requisite intent and the conviction was reversed.
In Erwin, the defendant was a rancher whose operation bordered B.L.M. land upon which another rancher grazed his cattle by permit. Erwin’s son drove two truckloads of cattle to auction, and, upon the sale of the animals, three were observed to be carrying the earmarks of the neighboring rancher. Apparently because of better forage, the Erwin property attracted the cattle from the B.L.M. land, and Erwin in the past had both returned strays and called the neighboring rancher to retrieve them. There also appeared to be fencing problems along the area where the B.L.M. land and the Erwin operation joined.
The Erwins explained at length during trial the process of culling, loading and transporting the cattle to auction. See 98 Idaho at 738, 572 P.2d 170. The end result was the extraction of a little more than 20% of the herd for sale, the culling and return of an additional 10% stray animals, and the final loading of the cattle after nightfall. The Erwins testified that occasionally strays were sent to market, and the brand commissioners agreed this was not an infrequent occurrence. Erwin also testified at trial of the possibility of mistakenly loading stray cattle — a mistake which he also had admitted was possible when confronted by the brand inspectors at the auction yard and questioned as to the earmarked animals.
This court stated in Erwin,
“Larceny is a crime of specific intent. The burden of proving the requisite mental state beyond a reasonable doubt belongs to the prosecution, [citation omitted] Recent U. S. Supreme Court decisions make it clear that any attempt to shift that burden to the defendant is an error of constitutional dimensions. At most, the defendant can be made to bear the burden of producing enough evidence to justify a reasonable doubt on the issue. But once the question has been raised, it is the prosecution which must prove the requisite mental state beyond any reasonable doubt, [citations omitted] No other procedure is compatible with safeguarding the presumption of innocence, ‘that bedrock “axiomatic and elementary” principle whose “enforcement lies at the foundation of the administration of our criminal law.” ’ ” 98 Idaho at 739-740.
While recognizing that intent may be proven by means of circumstantial evidence, the court reiterated the rule in Erwin that such evidence must not only be consistent with guilt, it must also be inconsistent with any reasonable theory of innocence. Erwin, supra, 98 Idaho at 740-41, 572 P.2d 170; State v. Wilson, 62 Idaho 282, 284, 111 P.2d 868 (1941); State v. Marcoe, 33 Idaho 284, 286, 193 P. 80 (1920). While the jury is the arbiter of the evidence, including the credibility of witnesses,
“at the same time, judicial review requires that we peruse that evidence to determine whether a reasonable mind would conclude that the defendant’s guilt as to each material element of the offense was proven beyond a reasonable doubt. Here our concern is with the element of felonious intent, and if the evidence is such that reasonable jurors must necessarily have a reasonable doubt as to the proof of that element, we can not *467allow the verdict to stand.” State v. Erwin, 98 Idaho at 740, 572 P.2d 170.
Appellant here stated at trial that he purchased, at auction and without inspection, the first large brood mare he could since he needed breeding stock but had to return quickly to Idaho and then to the racing circuit. Appellant testified that the animals at auction were quickly paraded through the sale ring and that he bid on three or four animals before being successful in acquiring a mare appearing to weigh around 1300 pounds for an amount between $300 and $400. He had the mare immediately loaded into his trailer and set out for Marsing. He arrived in the middle of the night, placed the horse in his pasture, and went to bed only to arise after a few hours sleep and leave once again for the out-of-state horse racing circuit. His wife, informed that they had a new horse, found exhibit 1 next to their home the morning following appellant’s return with the newly purchased mare.
Appellant and his wife fed this mare and treated it as their own, believing it to be their own, over the course of the summer. They had the animal bred during the season and decided to sell it only upon concluding that she was barren. Appellant and his wife testified that they had not seen the other mare, exhibit 4, until their neighbor came to recapture his strayed mules. Appellant at that time offered exhibit 4 to Quintana, believing it to be his neighbor’s lost mare, and indeed attempted to drive it in with the mules for transportation back to Quintana’s ranch.
Consistent with his belief, appellant sold exhibit 1 as his own. Only after being informed by the sheriff and brand inspector that the horse he sold belonged to someone else, and after being requested to settle his account with the livestock dealer, did appellant ever indicate that exhibit 4 might be his mare. He manifestly did so on the ground that if exhibit 1 was, in truth, not his horse, as he and his wife had believed, then exhibit 4 must have been his horse.
It appears from the record that the horses were similar enough in size and appearance that upon finding the mare at their home the morning following release and continually throughout the summer, appellant and his wife could reasonably believe that it was the mare he had purchased. Based upon Quintana’s testimony that exhibit 1 was a “work horse,” the state elicited testimony from various witnesses to the effect that work horses are generally heavier and of more solid build than “saddle horses.” Here, however, the “saddle” horse, exhibit 4, was but 40 to 50 pounds lighter than exhibit 1 and was described as “chunky” in appearance. The differences in weight, color and marking were not so striking that a person with the limited knowledge of the horse possessed by appellant would necessarily have decided that he was feeding and breeding the wrong animal.
It is our conclusion that the circumstantial evidence presented was consistent with appellant’s assertion that the sale of Quintana’s horse was but a mistake. The prosecution is required to prove all elements beyond a reasonable doubt and here “the evidence is such that reasonable jurors must necessarily have a reasonable doubt as to the proof [of the element of specific larcenous intent].” Erwin, supra, 98 Idaho at 740, 572 P.2d 170. The explanation offered by appellant, embodying a reasonable theory of innocence consistent with the facts and circumstances of the case, cannot be ignored. State v. Erwin, supra; State v. Wilson, supra; State v. Darrah, 60 Idaho 479, 484-5, 92 P.2d 143 (1939); State v. Marcoe, supra; State v. Seymour, 7 Idaho 257, 61 P. 1033 (1900). There was necessarily reasonable doubt as to the element of felonious intent and the evidence therefore fails to sustain the verdict. Accordingly, the conviction is reversed.
BISTLINE, J., and SCOGGIN, J. Pro Tern., concur.