AboutZoos, Since 2008


Mex­i­can wolf con­ser­va­tion suc­cess story and cap­tive pop­u­la­tion contribution

pub­lished 01 July 2017 | mod­i­fied 01 July 2017

Mexican wolf litter Brookfield zooThe con­ser­va­tion efforts to pro­tect and rein­tro­duce the Mex­i­can grey wolf in its native habi­tat are pay­ing off. As part of the Mex­i­can Grey Wolf Recov­ery Pro­gramme an adult female wolf from Brook­field Zoo, which is man­aged by the Chicago Zoo­log­i­cal Soci­ety was released to the wild in 2015 and gave birth to a lit­ter of six pup­pies. Addi­tion­ally, two wolf pup­pies born at Brook­field Zoo were placed in a wild pack, while now – in 2017 – a fur­ther cross-​fostering endeav­our among the wolf pop­u­la­tion appear to be successful.

Since 2003, the Chicago Zoo­log­i­cal Soci­ety (CZS), which man­ages Brook­field Zoo, has been a part­ner in the U.S. Fish and Wildlife Service’s (USFWS) Mex­i­can Wolf Recov­ery Pro­gramme. As part of this effort, adult wolves and their off­spring at Brook­field Zoo are poten­tial can­di­dates for release to the wild. When the Zoo’s female wolf Zana gave birth to a lit­ter of five pups on 22 April, USFWS offi­cials rec­om­mended that two pups from Brook­field Zoo’s lit­ter and two wild-​born pup­pies be cross-​fostered. In this par­tic­u­lar case, the objec­tive was to place two pups from Brook­field Zoo’s lit­ter with a wild pack and place two wild-​born pup­pies in the zoo’s pack.

Mexican wolf litter and mum Brookfield zooMex­i­can wolf lit­ter and mum at Brook­field zoo, May 2017.
Image credit: Chicago Zoo­log­i­cal Society.

His­tory, threats and con­ser­va­tion
Approx­i­mately 4,000 Mex­i­can wolves (Canis lupus bai­leyi) once roamed through­out vast por­tions of their his­toric range in Ari­zona, New Mex­ico, Texas, and Mex­ico. But, as human set­tle­ment inten­si­fied across the South­west in the early 1900s, wolves increas­ingly came into con­flict with live­stock oper­a­tions and other human activ­i­ties. Pri­vate, state, and fed­eral exter­mi­na­tion cam­paigns were waged against the wolf until, by the 1970’s, the Mex­i­can wolf had been all but elim­i­nated from the United States and Mexico.
In 1976, how­ever, a new era dawned for the Mex­i­can wolf. The Mex­i­can wolf, the rarest sub­species of grey wolf in North Amer­ica, was listed as endan­gered under the Endan­gered Species Act of 1973, a recog­ni­tion that the sub­species was in dan­ger of extinc­tion. The wolf was already func­tion­ally extinct in the South­west, and only occa­sional reports of wolves in Mex­ico con­firmed its con­tin­ued exis­tence in the wild. This crit­i­cal sit­u­a­tion even­tu­ally led to the devel­op­ment of a wolf recov­ery pro­gramme under the aus­pices of the US Fish and Wildlife Ser­vices – wild and cap­tive wolf pop­u­la­tions included.
As of August 2016, the pop­u­la­tion of the species in pro­fes­sional care is 245 indi­vid­u­als in 53 insti­tu­tions. The cap­tive pop­u­la­tion of Mex­i­can wolves is man­aged under the Asso­ci­a­tion of Zoos and Aquar­i­ums through the Mex­i­can Wolf Species Sur­vival Plan (AZA Mex­i­can Wolf SSP). This cap­tive man­age­ment pro­gramme is an essen­tial com­po­nent of Mex­i­can wolf recov­ery. The Mex­i­can Wolf SSP was ini­ti­ated in 1977 to 1980 with the cap­ture of the last remain­ing Mex­i­can wolves in the wild in Mex­ico. The SSP is a bi-​national cap­tive breed­ing pro­gramme between the U.S. and Mex­ico whose pri­mary pur­pose is to raise wolves for rein­tro­duc­tion into both the United States and Mex­ico. Specif­i­cally, the pur­pose of the SSP is to re-​establish the Mex­i­can wolf in the wild through cap­tive breed­ing, pub­lic edu­ca­tion, and research.
There are cur­rently a min­i­mum of 113 Mex­i­can grey wolves liv­ing in the wild in the U.S. and approx­i­mately 20 in Mexico.
Improv­ing the genet­ics of the wild Mex­i­can wolf pop­u­la­tion is essen­tial to their recov­ery. This cross-​foster pro­vides the oppor­tu­nity to improve the genet­ics of the pop­u­la­tion in the wild and to meet demo­graphic and genetic needs of the pop­u­la­tion in breed­ing and care facil­i­ties as well.

Sherry Bar­rett, USFWS’s Mex­i­can wolf recov­ery coordinator

Mexican wolf litter San MateoSan Mateo Mex­i­can wolf lit­ter born April 2017.
Photo credit: Photo cour­tesy of the Mex­i­can Wolf Inter­a­gency Field Team.
On 3 May, fol­low­ing a neona­tal exam­i­na­tion at the zoo, CZS ani­mal care staff trav­elled with a male and a female pup from Brook­field Zoo to New Mex­ico, where they met a team of biol­o­gists from the Mex­i­can Wolf Inter­a­gency Field Team. The pups were suc­cess­fully placed in the den of the San Mateo wild wolf pack, where the alpha female had recently given birth to her own lit­ter of six males and two females – one of the largest doc­u­mented lit­ters in the wild. At the same time, the CZS team received a male and a female puppy from the San Mateo pack for care and trans­fer to the zoo. CZS staff returned to Illi­nois and suc­cess­fully placed the wild-​born pup­pies in the den at Brook­field Zoo where Zana has been observed car­ing for the litter.

Wolf pack social struc­ture
Since the five pups, includ­ing the two born to the San Mateo wild wolf pack in New Mex­ico, emerged from the den in the Zoo’s enclo­sure on 16 May, vis­i­tors have an incred­i­ble oppor­tu­nity to wit­ness the com­plex social struc­ture of the wolf pack. A wolf pack usu­ally con­sists of an alpha male and female (the breed­ing pair), year­lings from the pre­vi­ous year’s lit­ter, and new pups. This is pre­cisely the struc­ture of the 10-​member pack at Brook­field Zoo: 5-​year-​old Zana and her 7-​year-​old mate Flint, three of their off­spring born in 2016, and the pup­pies. The species has bond­ing and care­giv­ing behav­iours in a social struc­ture that is sec­ond only to those of humans and pri­mates in com­plex­ity. Pack mem­bers use an array of vocal­iza­tions to com­mu­ni­cate, includ­ing howls, yips, squeals, growls, and barks. Guests vis­it­ing the zoo may wit­ness pack mem­bers dis­play­ing a vari­ety of facial expres­sions and body pos­tures that also play an impor­tant role in com­mu­ni­ca­tion. These dis­plays may sig­nify dom­i­nance or sub­mis­sion, play, and greet­ing cer­e­monies with lots of lick­ing. Addi­tion­ally, once the pups are weaned between six and eight weeks, they will whine, nudge, nib­ble, or lick the face and cor­ners of an adult’s mouth to encour­age it to regur­gi­tate food for them. Remark­ably, the pups born last year will assist their par­ents in rear­ing the new pups by regur­gi­tat­ing food for them and engag­ing them in play, among other behav­iours. In addi­tion, the year­lings will learn impor­tant parental skills from Zana and Flint for when they have their own litters.

CZS is thrilled to be a part of this impor­tant recov­ery endeav­our, and it has been extremely reward­ing to see wolves from Brook­field Zoo con­tribut­ing to con­ser­va­tion efforts for the Mex­i­can grey wolf wild pop­u­la­tion. The col­lab­o­ra­tion among all the par­tic­i­pat­ing orga­ni­za­tions is a true tes­ta­ment to the ded­i­ca­tion of every­one involved. We also hope our efforts help raise aware­ness of the impor­tance of the con­ser­va­tion of this North Amer­i­can species.

Bill Zei­gler, senior vice pres­i­dent of ani­mal pro­grammes for the Chicago Zoo­log­i­cal Society

This cross-​fostering endeav­our is not the first time CZS has con­tributed to the pro­gramme. In 2016, two wolf pup­pies born at the zoo were placed in a wild pack. Addi­tion­ally, in 2015, an adult female from Brook­field Zoo was released to the wild and gave birth to a lit­ter of six pup­pies. Sadly, she was found deceased in Jan­u­ary 2015, but her legacy lives on with her pups. Wildlife biol­o­gists have con­firmed obser­va­tions in Ari­zona (another release site) of wolves orig­i­nat­ing or asso­ci­ated with Brook­field Zoo.

More suc­cesses
The recent cross-​fostering is con­sid­ered a suc­cess. Zana, the alpha female at Brook­field Zoo, has been seen car­ing for the lit­ter, and although USFWS biol­o­gists do not have full visual access to the San Mateo lit­ter, they report the adult pair has con­tin­ued to stay in the area of the wild den site likely car­ing for the pup­pies.
For­tu­nately, not only cross-​fostering suc­cesses from the Brook­field Zoo pack are reported. In May, two Mex­i­can wolf pups born at the Endan­gered Wolf Cen­ter in Mis­souri (EWC) were placed in the den of the Pan­ther Creek Pack in Ari­zona, which was doc­u­mented with five pups. The two addi­tional pups from the EWC increased the total lit­ter size to seven. The Pan­ther Creek Pack was recently con­firmed as hav­ing a min­i­mum of 6 pups.

In addi­tion to cross-​fostering more suc­cess of the Mex­i­can wolf recov­ery efforts has recently been reported with the world’s first Mex­i­can wolf pup born from arti­fi­cially insem­i­nated frozen/​thawed semen at the EWC. The sperm used was col­lected in Jan­u­ary 2015 from a male Mex­i­can wolf at the EWC and stored at the Saint Louis Zoo’s cry­op­reser­va­tion gene bank – one of the world’s largest gene banks estab­lished specif­i­cally for the long-​term con­ser­va­tion of an endan­gered species.

(Source: Chicago Zoo­log­i­cal Soci­ety press release, 09.05.2017; Chicago Zoo­log­i­cal Soci­ety press release, 16.05.2017; CZS — Cen­ter for the Sci­ence of Ani­mal Care and Wel­fare – blog, May 2017; U.S. Fish and Wildlife Ser­vice press release, 24.10.2016; Endan­gered Wolf Cen­ter news blog, April 2017)

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