Meeting Abstract
Immune challenges can have large consequences on animals, such as decreased survival, which could be due to intensity. However, some survival-based costs may not show until later in life. To test if degree of immune challenge was related to survival, we issued one of four different doses of an immune challenge to nestling house sparrows and quantified survival during the nestling and fledgling periods. We injected a saline solution of lipopolysaccharide (LPS), a bacterially derived molecule that stimulates vertebrate immune systems, in doses of 0.0, 0.01, 0.1, or 1.0 mg LPS/kg body mass to nearly 150 10-day-old house sparrows during the summer of 2018. We also attached unique radio frequency identification (RFID) tags to each nestling. For nestling survival, we checked nests daily for mortality or fledging. For post-fledging survival, we placed antennae on bird feeders to detect RFID tags, showing which birds were still alive post-fledging. We predicted that as immune challenge intensity increased, survival would decrease. While the intensity did not seem to affect nestling survival, we detected fewer fledglings that received 1.0 mg LPS/kg body mass during the fledgling period. We cannot explain this, but possibly the energy invested in the immune response compromised the bird’s nutrient stores, increasing the chance of starvation post-fledging. The other doses did not show a survival difference, so we can infer that they did not have lasting effects. The trend manifested only at the highest dose, suggesting that less intense (and putatively common in nature) immune challenges may not have the same effects on survival.
