Individual variation and seasonality drive bird feeder use during winter in a Mediterranean climate

Abstract

Purposeful provisioning of food to wild animals is a widespread and growing activity that has the potential to impact populations and communities. Nevertheless, studies assessing use of recreational feeders by free‐living birds during winter are surprisingly rare and largely limited to regions with continental climates characterized by freezing temperatures and snow cover. In contrast, there is little information available regarding bird use of feeders within warmer climates during winter, despite widespread recreational feeding in these areas. In this study, we quantified visitation patterns to bird feeders in a Mediterranean climate to evaluate the relationship between feeder use and several environmental variables known to influence supplemental feeder use in continental climates. We established a network of bird feeders in Corvallis, Oregon, USA, that were filled with black oil sunflower ( Helianthus annuus ) seeds and equipped with radio frequency identification (RFID) data loggers that recorded >315,000 visits by 70 individual Black‐capped Chickadees ( Poecile atricapillus ) across a 5‐month period (October 2016–March 2017). We found extensive variation in feeder use, with individuals averaging 1–406 feeder visits/day and using 1–9 of the 21 feeders that were available; individual variability was largely consistent during the course of our study. At the population level, we found that feeder use decreased from the start of our study, and this decline continued through the period when foraging was most limited by daylight, including the winter solstice. In contrast to theoretical predictions and empirical work in continental climates, we found that weather variables did not drive feeder use and that feeder visits peaked at mid‐day and gradually decreased until sunset. Our study indicates that individual‐level differences combined with seasonality to drive feeder use patterns, and we conclude that use of supplemental feeders during winter in Mediterranean climates appears to differ notably from feeder use in continental climates.

Experimentally induced flight costs do not lead to increased reliance on supplemental food in winter by a small songbird

“…We also recorded body mass, right tarsus length and flattened right wing chord for each individual at its initial capture; body mass was again measured at the time when treatments were applied to each bird which allowed us to compare body mass of birds assigned to different treatments. Given extensive individual variation in feeder use by unmanipulated chickadees in our study system (Lajoie et al 2019), we began recording feeder visitation data in January 2017 to obtain pre-treatment data that allowed us to control for individual differences in feeder use. Following this pre-treatment period we conducted trapping sessions at all feeders across a five-week period (25 January-2 March 2017) to recapture as many previously banded chickadees as possible.…”

No effect of passive integrated transponder tagging method on survival or body condition in a northern population of Black‐capped Chickadees (Poecile atricapillus)

“…Over the last two decades, the use of passive integrated transponder (PIT) tags has increased dramatically (Bridge et al., 2019). In ornithological research, radio‐frequency identification (RFID) devices are often placed at discreet locations, such as feeders or nest boxes, that PIT‐tagged birds will repeatedly visit (Johnson et al., 2013; Lajoie et al., 2019). PIT tags and RFID devices have enabled a variety of research questions to be tackled on topics including foraging behavior (Lajoie et al., 2019; Moiron et al., 2018), movement ecology (Bailey et al., 2018; Matechou et al., 2015), social networks (Brandl et al., 2021; Evans et al., 2018; Firth et al., 2015), reproductive ecology (Schlicht & Kempenaers, 2015; Schuett et al., 2012; Zangmeister et al., 2009), and physiology (Skold‐Chiriac et al., 2015; Whitfield et al., 2015).…”

“…Several studies have evaluated the effects of PIT tags on small passerine birds and found no evidence for any adverse effects (Table 1). Results such as these have led to a widespread adoption of PIT tags for field studies in small birds, including Black‐capped Chickadees (circa 10–12 g) (Bailey et al., 2018; Evans et al., 2018; Lajoie et al., 2019) and even hummingbirds (<4 g) (Hou et al., 2015). However, while the study in hummingbirds demonstrated that they could be tracked effectively with PIT tags, the study did not compare survival or body condition relative to birds that did not receive implants (Hou et al., 2015).…”

“…Several studies have evaluated the effects of PIT tags on small passerine birds and found no evidence for any adverse effects (Table 1). Results such as these have led to a widespread adoption of PIT tags for field studies in small birds, including Black-capped Chickadees (circa 10-12 g) (Bailey et al, 2018;Evans et al, 2018;Lajoie et al, 2019) and even hummingbirds (<4 g) (Hou et al, 2015).…”

Behaviour of two species of psittacine birds at wild bird feeding sites in Australia

“…Wild bird feeding is one of the most common forms of wildlife interaction in the world (1)(2)(3)(4). It is particularly popular in developed countries with birds being fed at up to 75% of people's homes (2,(5)(6)(7)(8)(9)(10)(11)(12).…”