As of late, carnivorous birds like endangered California condors and animals like tigers are having fun with a better grade of beef at mealtime on the San Diego Zoo and San Diego Safari Park.
Zoo officers determine it’s a safer guess on the subject of chook flu.
The menu adjustment is simply the newest change the parks have applied as they’ve tried to stop the unfold of a lethal avian flu that’s killing birds and mammals across the globe.
Three years of working to guard unique and endangered animals in captivity has been no small feat for specialists on the two parks and at SeaWorld San Diego. With the unfold of chook flu displaying no signal of abating, they’ve tailor-made strategies to guard animals with as little disruption as doable.
And issues have gone properly. To this point, not one of the birds or animals within the collections of the zoo, Safari Park or SeaWorld have examined constructive for the pressure of the virus now inflicting outbreaks, referred to as H5N1.
That’s notable, on condition that 11 lifeless wild birds discovered on the sprawling grounds of Safari Park have examined constructive for the virus since 2022, when the outbreak reached California. At any time when lifeless birds are discovered, the parks ship them to a particular lab for testing.
Officers credit score shut surveillance of untamed migratory birds, a slew of biosecurity measures — and a bit luck.
Different zoos haven’t been so fortunate. An animal sanctuary in Washington reported shedding 20 large cats together with cougars and bobcats in late 2024 from the virus, whereas a harbor seal and Chilean flamingo have been felled at Chicago’s Lincoln Park Zoo in January. Final month in New York, not less than three geese on the Queens Zoo died due to chook flu, and a dozen different lifeless birds on the Bronx Zoo have been being examined.
For these managing animal care, their No. 1 concern stays virus transmission from contaminated wild birds. In order that they’ve put measures in place to attempt to decrease contact between wild birds and birds of their collections.
“We drain and clean the flamingo pond at least weekly so… any kind of bird waste is gone,” stated Eric Otjen, vice chairman of zoological operations at SeaWorld. Employees search for nests of untamed birds to take away, and the park has put in metallic spikes on railings and the tops of buildings to discourage roosting.
San Diego sits on the Pacific Flyway, a north-south route taken by migratory birds that may journey from Alaska south to South America. Wild birds that make the twice-a-year migration are thought of a threat as a result of they are often contaminated and present no indicators of sickness. Waterfowl similar to geese and geese will be of specific concern.
A wild chook surveillance program run by the U.S. Division of Agriculture serves as an early-warning system of flu infections. It reveals San Diego County had 36 constructive assessments for extremely pathogenic H5N1 chook flu from lifeless wild birds since 2022 — together with six positives this 12 months from samples collected in late 2024.
Throughout migration months, Safari Park workers relocates some birds into netted or coated habitat areas — however fewer birds than they moved earlier within the outbreak. Shifting birds will be disruptive to pure behaviors similar to nest constructing and selecting mates. Groups carry out a threat evaluation of every habitat yearly and decide mitigation steps from there.
“We’re trying to be good stewards, you know,” stated Dr. Hendrik Nollens, vice chairman of wildlife well being for San Diego Zoo Wildlife Alliance. “We’re trying to balance mitigating the risk and balancing that with allowing the natural behaviors.”
Carefully monitoring wild birds
The Safari Park is a well-liked cease for migrating birds, which might unfold chook flu via saliva, nasal secretions and feces. On any given day, wild birds will be seen subsequent to birds within the park’s assortment.
“We have decades of information on the wild birds that show up at the zoo and then show up at Safari Park. Over the years, we’ve learned which of these species actually are prone or susceptible or likely to carry avian influenza,” Nollens stated. “Because it turns out not every wild migratory bird is as risky — it’s not a homogenous risk.”
Classes realized within the final three years have formed protecting measures.
Now not are the tires of supply vehicles bringing provides to the parks being sanitized for worry they could carry the virus from locations like poultry farms. Chicken flu has decimated industrial poultry flocks, ensuing within the culling of tens of thousands and thousands of birds.
Stroll-through aviaries stay open to visitors, and staff solely should put on private protecting gear like gloves and masks in the event that they’re dealing with sick or lifeless wildlife discovered on park grounds.
As a substitute, officers take a look at identified methods the virus is being unfold, similar to consuming uncooked milk from contaminated dairy cows.
And regardless that chook flu has not been detected in beef cattle, the parks are actually solely shopping for human-grade beef — a better high quality that’s extra carefully regulated. “That supply chain obviously is closely scrutinized and monitored and tested by the USDA,” Nollens stated.
The parks have been already avoiding feeding uncooked poultry and uncooked eggs to their birds due to issues over virulent Newcastle illness, a distinct virus deadly to birds that often circulates in Southern California, he stated.
At one level, officers anxious about zoo guests who had chook pets at house — however “we’ve learned that’s not a realistic concern to us,” he added.
Each report of a constructive take a look at anyplace spurs officers to evaluate their biosecurity measures to ensure they aren’t lacking something. “With every positive, whether it’s a poultry operation or a wild flock or at another zoo, we try to learn, if it is even known, how the virus was introduced, how did it come in, to make sure that we have checked that box,” Nollens stated.
When the outbreak reached Southern California, SeaWorld San Diego quickly halted its bird-rescue program in October 2022 out of concern wild birds would carry the virus onto its property.
They restarted it after a number of months, though they not absorb sick western gulls or geese — widespread carriers of the virus, Otjen stated. Workers who reply to rescue calls don lengthy gloves, aprons, masks and goggles.
The marine park has taken different steps, similar to putting in coated trash cans in hopes of deterring hungry sea gulls. New flamingo feeding troughs boast a design that’s too tall for geese or gulls to get into — a change that wasn’t prompted by issues about chook flu however nonetheless helps preserve wild birds away from the meals, he stated.
Everlasting netting was put in over the Magellanic penguin habitat, which retains outdoors birds from stepping into the world. SeaWorld’s flamingos stay in an out of doors habitat with a pool however will be moved if there’s a necessity, Otjen stated.
“We are focusing on how we make sure there are as few wild birds that come into the park as possible,” he stated.
The lengthy historical past of chook flu
Chicken flu is assumed to have been round for tons of of years. In 1878, an sickness that killed poultry in Italy and different components of Europe was described as a “fowl plague.” By 1955 it was decided to be a kind A influenza virus, and in 1981, it turned generally known as avian influenza, in keeping with the U.S. Facilities for Illness Management and Prevention.
The H5N1 subtype of the virus will be traced again to poultry in Scotland in 1959 and in geese in China in 1996, which then unfold to poultry farms. Since then, there have been a number of waves of intercontinental transmission of the virus.
Infections have led to the loss of life and slaughter of greater than 633 million poultry birds worldwide between 2005 and 2024, in keeping with the World Animal Well being Info System, which tracks official knowledge on epidemiologically essential illnesses.
The virus additionally has reportedly sickened 70 individuals within the U.S. previously 12 months, and is thought to have prompted one loss of life in Louisiana. That affected person contracted H5N1 after publicity to birds in a yard flock and wild birds, state and federal officers stated.
In a commentary revealed within the journal Nature in January, three scientists warned that the specter of H5N1 “looms over global biodiversity” and sure has killed “multiple millions of wild animal individuals.”
However accounting for precise deaths is tough, the authors notice, due to “a pervasive lack of monitoring, testing and reporting — particularly in inaccessible areas and in disadvantaged countries.”
Condor deaths result in inoculation effort
The deaths of 21 critically endangered California condors in 2023 in Arizona prompted a distinct kind of response. For the primary time ever, federal officers accepted the emergency use of a vaccine in opposition to chook flu, and gave permission for trials to check the vaccines’ security and effectiveness.
After an preliminary take a look at of the vaccine on black vultures confirmed promise, the U.S. Fish and Wildlife Service carried out a trial involving 25 California condors —10 birds acquired two pictures, 10 birds acquired one and 5 birds served because the management group.
What it discovered recommended that the vaccine could scale back the severity of an an infection and the chance of loss of life, and that two pictures have been one of the best guess. Primarily based on the outcomes, regulators in December 2023 stated they might transfer ahead with plans to vaccinate captively managed and free-flying condors.
As of mid-March, 282 condors had obtained not less than one injection of the vaccine, with 182 of these totally vaccinated, a spokesperson for the U.S. Fish and Wildlife Service stated.
They’re usually attempting to vaccinate all California condors, she stated. Antibody titers in vaccinated condors — a gauge of their immunity — are being monitored, and the outcomes will inform future vaccination plans, the spokesperson added.
The entire condors at Safari Park have now obtained the vaccines, a park spokesperson stated, whereas a condor on the San Diego Zoo stays unvaccinated.
Nonetheless, the 2023 deaths in Arizona dealt a blow to the continuing condor restoration effort, with one official saying it set the conservation work again 10 years.
The species was getting ready to extinction in 1982, when 22 surviving condors within the wild have been captured and put right into a captive breeding program. Beginning in 1992, condors started to be reintroduced in California and later in Arizona and Baja California. As of late December, there have been greater than 560 condors in captivity and within the wild.
For his half, Nollens stated he could be open to contemplating vaccinating different zoo animals if that choice turns into out there sooner or later, “at least in some scenarios.”
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