Golden eagles in Nevada are facing a crisis, with a concerning decline in their population centered around the Dry Lake Valley, a historically important breeding ground north of Las Vegas. New data suggests the area has become what biologists are calling a “death vortex,” a place where eagles are dying at an alarming rate and failing to replenish their numbers.
The situation is particularly troubling because, until recently, Nevada’s golden eagle population was considered stable, hovering around 3,000 individuals as of . However, recent tracking data indicates a percent loss since , with a high probability of further declines. As Joe Barnes, a biologist with the U.S. Fish and Wildlife Service, puts it, there’s a “ percent odds that they’re declining, and it’s a fairly strong decline.”
Understanding the reasons behind this decline has been a complex undertaking. Researchers, including Barnes and James Golden, now at Colorado State University, have been employing a sophisticated tracking method: attaching transmitter-containing backpacks to both adult eagles and chicks. This process, described as requiring “guts” due to the challenges of approaching these wary birds and accessing their cliffside nests, has provided invaluable data on eagle movements and mortality.
The tracking revealed that Dry Lake Valley is acting as a “population sink,” meaning eagles from surrounding regions are flying in to occupy territories, only to perish. This makes accurate population assessment difficult, as the arrival of new birds can mask the loss of others. “Eagles are indistinguishable without transmitters,” Barnes explained. “When one bird dies and its territory is taken over by another bird, the new occupant can be mistaken for the old one, so the loss isn’t accounted for.” The tracking data highlighted this issue, revealing that while territories appeared occupied, they were frequently being turned over by incoming eagles.
The causes of death are multifaceted. Researchers have identified a combination of factors contributing to the eagles’ demise, including wildfire, drought, collisions with power lines, lead poisoning, and a virus that decimated the rabbit population – a primary food source for the birds. Barnes notes that eagles are capable of ceasing breeding for extended periods – “years, half a decade” – if conditions are sufficiently harsh.
Adding to the challenges, the increasing development of solar energy fields in Nevada is also impacting eagle habitat. Barnes expressed concern that “this type of land conversion, if you don’t do it wisely, can have really serious local impacts to wildlife and ecology.” A -square-kilometer solar energy field has been proposed for Dry Lake Valley, and its potential impact on the eagle population remains a concern.
The research, published in the December issue of the Journal of Raptor Research, underscores the precarious situation facing these apex predators. The hourly data collected from the transmitters – including speed, direction, location, and altitude – allowed researchers to map distinct eagle territories in the valley, providing a detailed picture of their movements and struggles.
Despite the grim outlook, researchers continue to monitor the situation. Barnes recently returned to the area in late January to assess breeding activity and food availability. While conditions remain challenging – with low jackrabbit numbers, poor vegetation growth, and extreme dryness – the eagles continue to persist, at least for now. The ongoing research is crucial to understanding the complex interplay of factors driving the decline and informing conservation efforts to protect this iconic species.
