Two methods of radio transmitter attachment and their effects on the behavior and energetics of captive long-tailed ducks (Clangula hyemalis) during winter

Abstract

Background: Attachment of external devices can have negative consequences for the health and fitness of subjects, but these effects are often overlooked. In preparation for a field study with small sea ducks, we investigated the effects of two types of external radio transmitter attachments on activity budgets and energetics of captive longtailed ducks (Clangula hyemalis) during winter. Methods:We conducted behavioral observations on 15 ducks over 3 months and measured oxygen consumption rates while resting on water and during preening. Ducks were either sham handled ('Control') or had transmitters attached with subcutaneous anchors ('Prongs') or Tesa tape/sutures ('Tesa'). Results:Following transmitter attachment, the activity budgets of Prong and Tesa birds changed significantly, while Controls remained largely unchanged. Prong and Tesa birds reduced locomotor activity (−58 and −54 %, respectively) and the proportion of time spent in water (−48 and −35 %, respectively), while they concomitantly increased time allocated to maintenance behavior (+98 and +151 %, respectively). Tesa birds recovered from these changes over time, at least partially, but Prong birds did not. Also, two of the five Prong birds developed a bacterial infection that spread from the attachment site. Retention time of transmitters was significantly greater for the Prong attachments (4 of 5 tags were retained for the entire 59-day study) than the Tesa technique (26.0 ± 3.2 days). Energy metabolism of ducks resting on water did not change significantly after transmitter attachment. Preening, the primary maintenance behavior, increased oxygen consumption rates by ~70 % over resting. The greater allocation of time to maintenance behavior after transmitter attachment most likely increased daily energy expenditure in these ducks, although the concurrent reduction in locomotor activity might have mitigated this effect. Ducks in our study had food ad libitum and were able to reduce locomotion after transmitter attachment without compromising food intake and, hence, energy balance. In the wild, this strategy might not be viable. Conclusions: Given the short retention time, the tape-based attachment technique we applied is not suitable if monitoring periods greater than ~2 to 3 weeks are desired. Both methods resulted in significant behavioral changes with energetic consequences that should be considered when planning to attach external transmitters to small sea ducks in the wild.

Reduction in adverse effects of tracking devices on waterfowl requires better measuring and reporting

“…Enstipp et al [24] compared tesasutured devices with subcutaneously anchored devices in Long-tailed Ducks and found that while birds with tesasutured devices recovered more rapidly from alterations of behaviour, tracking devices were lost after 26 days on average. Effects of other attachment methods were reported in original tracking studies.…”

“…Paquette et al [60] found female Mallards with subcutaneously anchored backpacks to spend less time on egg laying and incubation and to initiate fewer nests. Enstipp et al [24] found strongly altered behaviour in Long-tailed Ducks Clangula hyemalis with subcutaneous attachments, with increased preening behaviour and less time spent on the water, and two out of five individuals developed a bacterial infection at the site of attachment. Radio transmitters attached with prong and suture had no effect on reproduction in Wood Ducks [36].…”

Effects of harness-attached tracking devices on survival, migration, and reproduction in three species of migratory waterfowl

“…Attachment of tracking devices may increase the susceptibility of birds to being predated or shot, as shown by causes of death from tagged greater white-fronted geese in this study, of which out of 35 birds, 14 had been retrieved as shot, and 7 as predated by large birds of prey or fox during the spring migration following tag deployment. This may be caused by a change in behavior (e.g., increased time spent preening, [13]) or reduced flight maneuverability by the cross-sectional profile of the backpack tag causing additional drag [4], and perhaps not so much hunters targeting for marked geese [6]. Although our study found negative effects on return rates, our survival rates of tagged individuals were definitively higher than in some other studies [39], Harness attachments may have negative effects on survival, but are also likely to have non-lethal effects on migratory birds [26].…”

Neckband or backpack? Differences in tag design and their effects on GPS/accelerometer tracking results in large waterbirds

“…External tags have been reported to have no significant long-term effect on animals [59,71,78], but there have also been cases showing various negative effects on animal behaviour and survival [22,43,63,65,79,80]. Such effects can be intensified if the animal is flying or moving through water, depending on tag placement [47,48].…”

“…increased preening or biting the tag/harness [54,[58][59][60][61]. To decrease negative effects of tag aversion [62], it is necessary to shorten handling time and evaluate different types of tag placement and attachment methods for this species group [58,[63][64][65][66]. Welfare assessments should be made alongside considerations of data quality in order to balance animal discomfort against the amount and quality of scientific knowledge gained from the respective study [67].…”