IT'S ULTRASOUND SEASON AGAIN! John and the crew are working hard to capture as many pregnant females as possible and conduct ultrasounds before they give birth (ULTRASOUNDS). The purpose of the ultrasounds is to obtain a count of fetusus in utero in order to compare this number to the count of juveniles emerging from their nursery burrows in June. If a mother had four babies at her ultrasound, for example, but only three emerge from the nursery, then we know somewhere one of her babies failed to flourish. These numbers can be taken into consideration with other behavioral and environmental factors in determining how well a particular female prairie dog does in breeding and raising young, whether in a single year or over her lifetime.

IT'S DRAMA IN THE GRASSLAND. The mating season is always an exciting time in a prairie dog colony. Males run themselves ragged securing mates and enforcing territorial boundaries, often fighting violently with each other; and females must capitalize on a single day of estrus (sexual receptivity) for the entire year. As many as 65% of females may mate with multiple males in any given year (MATING SYSTEM). Called polyandry, this mating strategy has been correlated with higher fecundity (reproduction), genetically diverse offspring, and healthier juveniles.

This year so far we have had more females than expected who have mated with only one male, while others have predictably taken advantage of the males available. One of our females even copulated with four males on her day of estrus. As you can probably imagine, the mating season is full of dramatic courtships, disputes, fights, mating calls, and mostly underground copulations.

Coyotes, badgers, golden eagles, and other predators (THE PREY ANIMAL) have been sighted since the start of spring emergences (coming out of hibernation), and their appearances demonstrate the risk these prairie dogs take when they become distracted by mating activities.

As for John and the Prairie Dog Squad, the mating season means long, busy hours taking data on multiple copulations in a single day. Yesterday we had 11 females go into estrus at our study colony! Estrous females and dominant males stay up late into the night on the day they copulate, taking advantage of the absolute last glow of dusk to forage and find mating partners. This further puts the prairie dogs in danger, as dusk is a favorite hunting time for coyotes and badgers, and prairie dogs have poor eyesight in dim lighting.

We still have up to two weeks remaining of the mating season, and so far more than 30 of our marked females have gone into estrus. While an occasional female is still waking up late from hibernation, we are expecting close to 20 more to go into estrus over the next several days. That’s a lot of action, a lot of data, a lot of ultrasounds in April/May, and a lot of juveniles to expect come June!

UPDATE FROM REDONDO MEADOWS. As of yesterday, a single prairie dog has emerged from hibernation at our post-plague colony site. If you'll recall, this site had 12 prairie dogs in July 2017, of which 6 were found and marked before going down for the winter in September 2017. We do not know if the missing 6 fell prey to predators or if they went into hibernation early.

So far our single winter survivor is yearling female Black Butt (BB), who was a juvenile in July 2017 and had two siblings. Yearling females usually mate in their first year, so there is hope a male from a nearby subcolony will find her when she goes into estrus.

We also still hold hope for BB's siblings and the remainder of the other prairie dogs at the site to emerge from hibernation soon. Stay tuned and fingers crossed!

OUR FIRST FEMALE IS UP! We haven't been able to get a photograph of her, as she's been hiding in tall grass, but RSRAB finally came up late in the day yesterday, and was up again today. RSRAB stands for Racing Stripes Ring Around the Belly. This means her unique marking is a racing stripe on each side of her flank, and a ring that encircles her torso. We'll post a photo as soon as we're able to get one!

No additional females popped up today, but we're confident many will be coming aboveground in the coming days. And shortly thereafter: the mating season!

SPRING AROUSALS ARE GOING...a bit slow this year. John reports that of all the species he's studied (black-tailed, Gunnison's, Utah, and white-tailed), Gunnison's prairie dogs are the worst in bad weather; and here at the Valles Caldera National Preserve, we've had a bit of winter weather coming through, which may explain the slow wakeups. Regardless, we're seeing more prairie dogs every day, though we're still waiting for those females! The 51 marked males (see PURPOSE & METHODS for more on marking) we have seen so far are also eagerly awaiting the females, and some are already disputing over territories. Once the females pop up, mating season will follow shortly after. It's our most anticipated time of the year!