Daily Postcard: An antler shed in a montane grassland viewed Friday at Valles Caldera National Preserve. Every winter, reduced daylight causes testosterone levels in male deer and elk to drop, eventually leading to the shedding of their antlers. When spring arrives, it turns into a multi-species scavenger hunt. Shed antlers are a rich source of nutrients for wildlife that find them on forest or valley floors. Because they are such an important supplement to the diets of wildlife in this high-elevation ecosystem, shed collecting is not permitted within Valles Caldera. Next time you spot a shed antler while visiting the park, take a close look for tiny marks where critters have been nibbling on it to kickstart their springtime diets. To find park rules and regulations, click here. Courtesy/NPS