Radiomarking brood‐rearing mallard females: Implications for juvenile survival

Abstract

Radiotelemetry is frequently used to measure habitat use, movements, and survival in birds; presumably, outfitting adult females with radiotransmitters does not influence juvenile survival, but this critical assumption is rarely tested. We evaluated whether the timing or type of transmitter deployed on adult female mallards (Anas platyrhynchos) reduced duckling survival estimates in the Canadian Prairie Pothole Region, 1993-1995. The best-approximating model suggests that, compared with 2 other trap-transmitter combinations, ducklings raised by mallard females trapped prior to nest initiation and outfitted with anchorsuture transmitters had poor survival. The 30-day survival rate of ducklings raised by female mallards equipped with anchor-suture transmitters prior to nest initiation was lower than survival of ducklings attended by females equipped prior to nest initiation with abdominally implanted transmitters or females marked during late incubation with anchor-suture transmitters. Studies of reproductive success deploying anchor-suture transmitters on female waterfowl trapped prior to nest initiation may have biased results because of possible negative consequences to offspring survival. ß 2012 The Wildlife Society.

Effects of satellite transmitters on captive and wild mallards

“…Several investigations also reported minimal transmitter effects on behavior of nesting and brood‐rearing mallards (Rotella et al , Dzus and Clark ). However, multiple studies emphasized differential effects on birds, depending on the type of mounting system used (Paquette et al , Guyn and Clark , Phillips et al ; but see Pietz et al ), duration of time that birds carried equipment (Bloom et al ), and transmitter mass (Hooge ). Satellite systems available to date have been larger and heavier than previously used VHF systems, and the harnesses we tested encircled the entire bird body.…”

Variation in mallard vital rates in Canadian Aspen Parklands: The Prairie Habitat Joint Venture assessment

“…We marked most captured females with Telonics model IMP/150 22-g abdominally implanted radio-transmitters (Telonics, Mesa, AZ; Olsen et al 1992, Rotella et al 1993, but early in the study we fitted approximately 25% of the birds on 4 study areas (Hamiota, MB; Shoal Lake, MB; Kutawa Lake, SK; and Camp Lake, AB) and 50% of the birds on 1 study area (Erskine, AB) with backmounted anchor or anchor-suture transmitters (Paquette et al 1997). After documenting several subtle but deleterious effects of back-mounted transmitters on breeding productivity, for example, initiating nests later, devoting fewer days to egglaying and incubation, and experiencing reduced duckling survival (Paquette et al 1997, Bloom et al 2012b), we deleted these birds from further analysis, reducing our sample on these 5 study areas to 67-100 radio-marked birds. We also fitted every second female in 1993 with a unique set of nylon nasal discs (Lokemoen and Sharp 1985).…”

“…We fitted nest-trapped females with 4-or 8-g Advanced Telemetry Systems model 357 or 2040 back-mounted transmitters, respectively (Advanced Telemetry Systems, Isanti, MN) attached with anchor, glue (pre-1998), and sutures (Mauser and Jarvis 1991, Pietz et al 1995, Paquette et al 1997. Ducklings from nest-trapped females using this transmitter attachment method experienced similar survival rates as ducklings from females with implanted transmitters (Bloom et al 2012b). To reduce the likelihood of abandonment, we anesthetized females with methoxyflurane before placing them back on their nests (Rotella and Ratti 1990).…”

Mallard brood movements and survival in an urbanized landscape

“…Mallard females may increase preening and decrease foraging behaviors following transmitter deployment, which may reduce attentiveness to ducklings or increase the risk of brood abandonment (Gilmer et al 1975, Rotella and Ratti 1992a, Pietz et al 1993; however, trapping females during late incubation (as is often done to study ducklings; Guyn and Clark 1999, Amundson and Arnold 2011, Garrick et al 2017 does not necessarily reduce duckling survival compared to trapping pre-nesting or mid-incubation (Bergmann et al 1994, Bloom et al 2012.…”