FORCED MOLT IN FOUR JUVENILE YELLOW-EYED PENGUINS (MEGADYPTES ANTIPODES)

Abstract

Penguins are dependent on waterproof plumage for survival. The molt in sub-Antarctic penguin species is a seasonal and catastrophic process during which the animals go through periods of fasting and high levels of stress. Their entire plumage is usually replaced in 3 wk. Attempts at consistent hormonal induction of molt in penguins have been unsuccessful. Four Yellow-eyed Penguins ( Megadyptes antipodes ) were referred for treatment at Wildbase, Massey University, Palmerston North, New Zealand, in late April 2014, following loss of waterproofing, feather breakage, increased body weight, pododermatitis, and damage to caudal feathers from hock sitting. Feather plucking of damaged areas to stimulate feather regrowth was attempted with poor results. Waiting 10-12 mo for a natural molt was not tenable. Catastrophic molt was induced by treatment with 10 g/kg of fresh beef thyroid gland orally once a day. The molt was complete in 18-26 d during which the animals regained full plumage and waterproofing after feather regrowth. The forced molt feathers had abnormal pigmentation but were of sufficient quality to allow release of the birds back to the wild.

Organ weights and histopathology of double-crested cormorants ( Phalacrocorax auritus ) dosed orally or dermally with artificially weathered Mississippi Canyon 252 crude oil

“…The thyroid gland is a critical organ for maintaining general metabolic rate (Olson et al, 1999). Thyroid hormones stimulate general metabolism and new feather growth (Webster et al, 2016). Additional causes for the change in the thyroid gland including normal molting and/or exposure to environmental goitrogenic substances should have resulted in similar changes across both groups (BaJaJ et al, 2016).…”

Successful resection of an osteoma in a great horned owl (Bubo virginianus) with subsequent lack of regional feather regrowth

“…Various methods have been described to attempt induction of feather regrowth prior to the next natural moult, including hormonal additives such as progesterone, thyroxine, thyroid hormone or Elityran (a synthetic non-apeptide analogue of gonadotropin releasing hormone); feeding beef thyroid; removal of food (for a period long enough for involution of the reproductive tract) and water (for up to 3 days); reduction in photoperiod or manipulation of dietary minerals. [32][33][34][35][36][37][38][39][40][41] However, due to inconsistent results, ethical concerns and lack of extensive understanding of side effects, such techniques may not be suitable for all individuals. In one of the authors' experience, and likewise noted by colleagues, manually pulling damaged feathers can induce feather regrowth, even outside of the natural moulting period.…”