No real secret to growing the easiest hybrids with Anigozanthus flavidus parentage, but they do prefer both good drainage and regular warm season irrigation. In habitat they even well tolerate seasonal winter flooding and summer wild fires. Full sun, good air circulation, planting out in cooler months to minimize drought stress,(typical nursery container mixes for them very quickly dry out if you aren't adequately wetting the root ball, and probably accounts for most plant deaths). They are extremely easy once established, but don't crowd the foliage or insist on overhead spray irrigation which encourages ink spot disease.

Neither animal is native to the others natural habitat so I doubt they would consume similar plants.....but I might be wrong! Kangaroos do eat Kangaroo Paw as per the link. Maybe check if deer eat plants in the Kangaroo Paw Haemodoraceae family of herbaceous plants related to the lilies (Amaryllidaceae). Also Google australia might turn something up. Good luck! Here is a link that might be useful: http://www.abc.net.au/science/news/stories/2004/1052204.htm

If it is still wilting even with moist soil, then it could be the opposite problem of staying too wet! Kangaroo Flower wants good drainage, but isn't drought tolerant until it is well rooted in. If it is one of the more difficult to grow species/cultivars other than an Anigozanthus flavidus type, they can be touchy regardless of what you do, especially if it is allowed to dry out and then you try to revive it. I don't think fertilizer would help at this point, if the flower stalks don't revive, cut them off at ground level and see if the plant settles in.

I have found that Anigozanthos is quite long lived especially in neglected areas or areas that did not and do not receive wonderfully rich organic compost applications. That first photo is a commercial shopping center bed that was planted about a decade ago ( Hopmonk Brewery in Novato ) . It receives some commercial level maintenance attention but it is not lovingly cared for by a home gardener ( no disrespect to commercially cared for landscape companies) . The second image is of a residential project in Belvedere that was also planted about 10 years ago. It has not received 'attention to detail' maintenance over the years yet the Anigozanthos is doing well . The Leucadendron Jesters have not been adequately pruned and are out of scale now and looking rangey. I have some 'neglectful' areas in my own experimental home garden. Some of the kangaroo paws are going on 15 years old and still bloom despite the poor soil and infringing shade from the overhead oak trees . I believe that true to their native habitat that the Anigozanthos prefers lean soil fertility conditions and good drainage for it to be successful in the long run. Good gardening to you.